diff --git a/boa/src/builtins/console/mod.rs b/boa/src/builtins/console/mod.rs
index e96beebe09c..efbc5b78e21 100644
--- a/boa/src/builtins/console/mod.rs
+++ b/boa/src/builtins/console/mod.rs
@@ -20,8 +20,8 @@ use crate::{
     builtins::BuiltIn,
     object::ObjectInitializer,
     property::Attribute,
-    value::{display::display_obj, RcString, Value},
-    BoaProfiler, Context, Result,
+    value::{display::display_obj, Value},
+    BoaProfiler, Context, JsString, Result,
 };
 use rustc_hash::FxHashMap;
 use std::time::SystemTime;
@@ -137,8 +137,8 @@ pub fn formatter(data: &[Value], context: &mut Context) -> Result<String> {
 /// This is the internal console object state.
 #[derive(Debug, Default)]
 pub(crate) struct Console {
-    count_map: FxHashMap<RcString, u32>,
-    timer_map: FxHashMap<RcString, u128>,
+    count_map: FxHashMap<JsString, u32>,
+    timer_map: FxHashMap<JsString, u128>,
     groups: Vec<String>,
 }
 
diff --git a/boa/src/builtins/json/mod.rs b/boa/src/builtins/json/mod.rs
index 05365b19613..d5d828e0c31 100644
--- a/boa/src/builtins/json/mod.rs
+++ b/boa/src/builtins/json/mod.rs
@@ -15,12 +15,13 @@
 
 use crate::{
     builtins::BuiltIn,
+    object::Object,
     object::ObjectInitializer,
     property::{Attribute, DataDescriptor, PropertyKey},
+    symbol::WellKnownSymbols,
     value::IntegerOrInfinity,
     BoaProfiler, Context, Result, Value,
 };
-use crate::{object::Object, symbol::WellKnownSymbols};
 use serde::Serialize;
 use serde_json::{self, ser::PrettyFormatter, Serializer, Value as JSONValue};
 
diff --git a/boa/src/builtins/object/for_in_iterator.rs b/boa/src/builtins/object/for_in_iterator.rs
index 56e71b152b3..f0193be21c1 100644
--- a/boa/src/builtins/object/for_in_iterator.rs
+++ b/boa/src/builtins/object/for_in_iterator.rs
@@ -1,12 +1,12 @@
-use crate::value::RcString;
 use crate::{
     builtins::{function::make_builtin_fn, iterable::create_iter_result_object},
     gc::{Finalize, Trace},
     object::{GcObject, ObjectData},
+    property::PropertyKey,
     property::{Attribute, DataDescriptor},
-    BoaProfiler, Context, Result, Value,
+    symbol::WellKnownSymbols,
+    BoaProfiler, Context, JsString, Result, Value,
 };
-use crate::{property::PropertyKey, symbol::WellKnownSymbols};
 use rustc_hash::FxHashSet;
 use std::collections::VecDeque;
 
@@ -20,8 +20,8 @@ use std::collections::VecDeque;
 #[derive(Debug, Clone, Finalize, Trace)]
 pub struct ForInIterator {
     object: Value,
-    visited_keys: FxHashSet<RcString>,
-    remaining_keys: VecDeque<RcString>,
+    visited_keys: FxHashSet<JsString>,
+    remaining_keys: VecDeque<JsString>,
     object_was_visited: bool,
 }
 
diff --git a/boa/src/builtins/regexp/mod.rs b/boa/src/builtins/regexp/mod.rs
index fa1511bc4ce..a20a9595ce0 100644
--- a/boa/src/builtins/regexp/mod.rs
+++ b/boa/src/builtins/regexp/mod.rs
@@ -17,8 +17,8 @@ use crate::{
     object::{ConstructorBuilder, FunctionBuilder, GcObject, ObjectData, PROTOTYPE},
     property::{Attribute, DataDescriptor},
     symbol::WellKnownSymbols,
-    value::{IntegerOrInfinity, RcString, Value},
-    BoaProfiler, Context, Result,
+    value::{IntegerOrInfinity, Value},
+    BoaProfiler, Context, JsString, Result,
 };
 use regexp_string_iterator::RegExpStringIterator;
 use regress::Regex;
@@ -650,7 +650,7 @@ impl RegExp {
     /// [spec]: https://tc39.es/ecma262/#sec-regexpexec
     pub(crate) fn abstract_exec(
         this: &Value,
-        input: RcString,
+        input: JsString,
         context: &mut Context,
     ) -> Result<Value> {
         // 1. Assert: Type(R) is Object.
@@ -694,7 +694,7 @@ impl RegExp {
     /// [spec]: https://tc39.es/ecma262/#sec-regexpbuiltinexec
     pub(crate) fn abstract_builtin_exec(
         this: &Value,
-        input: RcString,
+        input: JsString,
         context: &mut Context,
     ) -> Result<Value> {
         // 1. Assert: R is an initialized RegExp instance.
@@ -1160,7 +1160,7 @@ impl RegExp {
         }
 
         // 12. Let accumulatedResult be the empty String.
-        let mut accumulated_result = RcString::from("");
+        let mut accumulated_result = JsString::new("");
 
         // 13. Let nextSourcePosition be 0.
         let mut next_source_position = 0;
@@ -1227,7 +1227,7 @@ impl RegExp {
 
             // k. If functionalReplace is true, then
             // l. Else,
-            let replacement: RcString;
+            let replacement: JsString;
             if functional_replace {
                 // i. Let replacerArgs be « matched ».
                 let mut replacer_args = vec![Value::from(matched)];
@@ -1553,7 +1553,7 @@ impl RegExp {
 ///  - [ECMAScript reference][spec]
 ///
 /// [spec]: https://tc39.es/ecma262/#sec-advancestringindex
-fn advance_string_index(s: RcString, index: usize, unicode: bool) -> usize {
+fn advance_string_index(s: JsString, index: usize, unicode: bool) -> usize {
     // Regress only works with utf8, so this function differs from the spec.
 
     // 1. Assert: index ≤ 2^53 - 1.
diff --git a/boa/src/builtins/regexp/regexp_string_iterator.rs b/boa/src/builtins/regexp/regexp_string_iterator.rs
index 99dcbfd3275..87195e326a3 100644
--- a/boa/src/builtins/regexp/regexp_string_iterator.rs
+++ b/boa/src/builtins/regexp/regexp_string_iterator.rs
@@ -17,15 +17,14 @@ use crate::{
     object::{GcObject, ObjectData},
     property::{Attribute, DataDescriptor},
     symbol::WellKnownSymbols,
-    value::RcString,
-    BoaProfiler, Context, Result, Value,
+    BoaProfiler, Context, JsString, Result, Value,
 };
 
 // TODO: See todos in create_regexp_string_iterator and next.
 #[derive(Debug, Clone, Finalize, Trace)]
 pub struct RegExpStringIterator {
     matcher: Value,
-    string: RcString,
+    string: JsString,
     global: bool,
     unicode: bool,
     completed: bool,
@@ -33,7 +32,7 @@ pub struct RegExpStringIterator {
 
 // TODO: See todos in create_regexp_string_iterator and next.
 impl RegExpStringIterator {
-    fn new(matcher: Value, string: RcString, global: bool, unicode: bool) -> Self {
+    fn new(matcher: Value, string: JsString, global: bool, unicode: bool) -> Self {
         Self {
             matcher,
             string,
@@ -51,7 +50,7 @@ impl RegExpStringIterator {
     /// [spec]: https://tc39.es/ecma262/#sec-createregexpstringiterator
     pub(crate) fn create_regexp_string_iterator(
         matcher: &Value,
-        string: RcString,
+        string: JsString,
         global: bool,
         unicode: bool,
         context: &mut Context,
diff --git a/boa/src/builtins/string/mod.rs b/boa/src/builtins/string/mod.rs
index a66889ae11b..b6829c933ec 100644
--- a/boa/src/builtins/string/mod.rs
+++ b/boa/src/builtins/string/mod.rs
@@ -21,8 +21,7 @@ use crate::{
     object::{ConstructorBuilder, Object, ObjectData},
     property::Attribute,
     symbol::WellKnownSymbols,
-    value::{RcString, Value},
-    BoaProfiler, Context, Result,
+    BoaProfiler, Context, JsString, Result, Value,
 };
 use std::{
     char::{decode_utf16, from_u32},
@@ -31,7 +30,7 @@ use std::{
 };
 use unicode_normalization::UnicodeNormalization;
 
-pub(crate) fn code_point_at(string: RcString, position: i32) -> Option<(u32, u8, bool)> {
+pub(crate) fn code_point_at(string: JsString, position: i32) -> Option<(u32, u8, bool)> {
     let size = string.encode_utf16().count() as i32;
     if position < 0 || position >= size {
         return None;
@@ -170,7 +169,7 @@ impl String {
                     .clone()
             }
             Some(ref value) => value.to_string(context)?,
-            None => RcString::default(),
+            None => JsString::default(),
         };
 
         if new_target.is_undefined() {
@@ -202,7 +201,7 @@ impl String {
         Ok(this)
     }
 
-    fn this_string_value(this: &Value, context: &mut Context) -> Result<RcString> {
+    fn this_string_value(this: &Value, context: &mut Context) -> Result<JsString> {
         match this {
             Value::String(ref string) => return Ok(string.clone()),
             Value::Object(ref object) => {
@@ -685,10 +684,9 @@ impl String {
 
         // 11. If functionalReplace is true, then
         // 12. Else,
-        let replacement: RcString;
-        if functional_replace {
+        let replacement = if functional_replace {
             // a. Let replacement be ? ToString(? Call(replaceValue, undefined, « searchString, 𝔽(position), string »)).
-            replacement = context
+            context
                 .call(
                     &replace_value,
                     &Value::Undefined,
@@ -698,22 +696,22 @@ impl String {
                         this_str.clone().into(),
                     ],
                 )?
-                .to_string(context)?;
+                .to_string(context)?
         } else {
             // a. Assert: Type(replaceValue) is String.
             // b. Let captures be a new empty List.
             let captures = Vec::new();
 
             // c. Let replacement be ! GetSubstitution(searchString, string, position, captures, undefined, replaceValue).
-            replacement = get_substitution(
+            get_substitution(
                 search_str.to_string(),
                 this_str.to_string(),
                 position.unwrap(),
                 captures,
                 Value::undefined(),
                 replace_value.to_string(context)?.to_string(),
-            )?;
-        }
+            )?
+        };
 
         // 13. Return the string-concatenation of preserved, replacement, and the substring of string from position + searchLength.
         Ok(format!(
@@ -862,9 +860,9 @@ impl String {
     /// Performs the actual string padding for padStart/End.
     /// <https://tc39.es/ecma262/#sec-stringpad/>
     fn string_pad(
-        primitive: RcString,
+        primitive: JsString,
         max_length: i32,
-        fill_string: Option<RcString>,
+        fill_string: Option<JsString>,
         at_start: bool,
     ) -> Value {
         let primitive_length = primitive.len() as i32;
@@ -1480,7 +1478,7 @@ pub(crate) fn get_substitution(
     captures: Vec<Value>,
     _named_captures: Value,
     replacement: StdString,
-) -> Result<RcString> {
+) -> Result<JsString> {
     // 1. Assert: Type(matched) is String.
 
     // 2. Let matchLength be the number of code units in matched.
diff --git a/boa/src/bytecompiler.rs b/boa/src/bytecompiler.rs
index 93142150849..270ca1a430c 100644
--- a/boa/src/bytecompiler.rs
+++ b/boa/src/bytecompiler.rs
@@ -4,9 +4,9 @@ use crate::{
         op::{AssignOp, BinOp, BitOp, CompOp, LogOp, NumOp, UnaryOp},
         Const, Node,
     },
-    value::{RcBigInt, RcString},
+    value::RcBigInt,
     vm::{CodeBlock, Opcode},
-    Value,
+    JsString, Value,
 };
 
 use std::collections::HashMap;
@@ -34,7 +34,7 @@ fn u64_to_array(value: u64) -> [u8; 8] {
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 enum Literal {
-    String(RcString),
+    String(JsString),
     BigInt(RcBigInt),
 }
 
@@ -64,7 +64,7 @@ enum Access<'a> {
 pub struct ByteCompiler {
     code_block: CodeBlock,
     literals_map: HashMap<Literal, u32>,
-    names_map: HashMap<RcString, u32>,
+    names_map: HashMap<JsString, u32>,
     loops: Vec<LoopControlInfo>,
 }
 
@@ -111,7 +111,7 @@ impl ByteCompiler {
             return *index;
         }
 
-        let name: RcString = name.into();
+        let name = JsString::new(name);
         let index = self.code_block.names.len() as u32;
         self.code_block.names.push(name.clone());
         self.names_map.insert(name, index);
diff --git a/boa/src/lib.rs b/boa/src/lib.rs
index f7b0d8c3499..1afa7ddc603 100644
--- a/boa/src/lib.rs
+++ b/boa/src/lib.rs
@@ -54,6 +54,7 @@ pub mod object;
 pub mod profiler;
 pub mod property;
 pub mod realm;
+pub mod string;
 pub mod symbol;
 // syntax module has a lot of acronyms
 #[allow(clippy::upper_case_acronyms)]
@@ -71,7 +72,7 @@ pub(crate) use crate::{exec::Executable, profiler::BoaProfiler};
 
 // Export things to root level
 #[doc(inline)]
-pub use crate::{context::Context, symbol::JsSymbol, value::Value};
+pub use crate::{context::Context, string::JsString, symbol::JsSymbol, value::Value};
 
 use crate::syntax::{
     ast::node::StatementList,
diff --git a/boa/src/object/iter.rs b/boa/src/object/iter.rs
index c0b6d4813f1..f5b2f10cedb 100644
--- a/boa/src/object/iter.rs
+++ b/boa/src/object/iter.rs
@@ -1,5 +1,5 @@
 use super::{Object, PropertyDescriptor, PropertyKey};
-use crate::{value::RcString, JsSymbol};
+use crate::{JsString, JsSymbol};
 use std::{collections::hash_map, iter::FusedIterator};
 
 impl Object {
@@ -109,7 +109,7 @@ impl Object {
 #[derive(Debug, Clone)]
 pub struct Iter<'a> {
     indexed_properties: hash_map::Iter<'a, u32, PropertyDescriptor>,
-    string_properties: hash_map::Iter<'a, RcString, PropertyDescriptor>,
+    string_properties: hash_map::Iter<'a, JsString, PropertyDescriptor>,
     symbol_properties: hash_map::Iter<'a, JsSymbol, PropertyDescriptor>,
 }
 
@@ -342,10 +342,10 @@ impl FusedIterator for IndexPropertyValues<'_> {}
 
 /// An iterator over the `String` property entries of an `Object`
 #[derive(Debug, Clone)]
-pub struct StringProperties<'a>(hash_map::Iter<'a, RcString, PropertyDescriptor>);
+pub struct StringProperties<'a>(hash_map::Iter<'a, JsString, PropertyDescriptor>);
 
 impl<'a> Iterator for StringProperties<'a> {
-    type Item = (&'a RcString, &'a PropertyDescriptor);
+    type Item = (&'a JsString, &'a PropertyDescriptor);
 
     #[inline]
     fn next(&mut self) -> Option<Self::Item> {
@@ -369,10 +369,10 @@ impl FusedIterator for StringProperties<'_> {}
 
 /// An iterator over the string keys (`RcString`) of an `Object`.
 #[derive(Debug, Clone)]
-pub struct StringPropertyKeys<'a>(hash_map::Keys<'a, RcString, PropertyDescriptor>);
+pub struct StringPropertyKeys<'a>(hash_map::Keys<'a, JsString, PropertyDescriptor>);
 
 impl<'a> Iterator for StringPropertyKeys<'a> {
-    type Item = &'a RcString;
+    type Item = &'a JsString;
 
     #[inline]
     fn next(&mut self) -> Option<Self::Item> {
@@ -396,7 +396,7 @@ impl FusedIterator for StringPropertyKeys<'_> {}
 
 /// An iterator over the string values (`Property`) of an `Object`.
 #[derive(Debug, Clone)]
-pub struct StringPropertyValues<'a>(hash_map::Values<'a, RcString, PropertyDescriptor>);
+pub struct StringPropertyValues<'a>(hash_map::Values<'a, JsString, PropertyDescriptor>);
 
 impl<'a> Iterator for StringPropertyValues<'a> {
     type Item = &'a PropertyDescriptor;
diff --git a/boa/src/object/mod.rs b/boa/src/object/mod.rs
index 3da5b7ece20..88efd42b4ec 100644
--- a/boa/src/object/mod.rs
+++ b/boa/src/object/mod.rs
@@ -15,8 +15,8 @@ use crate::{
     context::StandardConstructor,
     gc::{Finalize, Trace},
     property::{AccessorDescriptor, Attribute, DataDescriptor, PropertyDescriptor, PropertyKey},
-    value::{RcBigInt, RcString, Value},
-    BoaProfiler, Context, JsSymbol,
+    value::{RcBigInt, Value},
+    BoaProfiler, Context, JsString, JsSymbol,
 };
 use rustc_hash::FxHashMap;
 use std::{
@@ -69,7 +69,7 @@ pub struct Object {
     pub data: ObjectData,
     indexed_properties: FxHashMap<u32, PropertyDescriptor>,
     /// Properties
-    string_properties: FxHashMap<RcString, PropertyDescriptor>,
+    string_properties: FxHashMap<JsString, PropertyDescriptor>,
     /// Symbol Properties
     symbol_properties: FxHashMap<JsSymbol, PropertyDescriptor>,
     /// Instance prototype `__proto__`.
@@ -93,7 +93,7 @@ pub enum ObjectData {
     Function(Function),
     Set(OrderedSet<Value>),
     SetIterator(SetIterator),
-    String(RcString),
+    String(JsString),
     StringIterator(StringIterator),
     Number(f64),
     Symbol(JsSymbol),
@@ -216,7 +216,7 @@ impl Object {
     #[inline]
     pub fn string<S>(value: S) -> Self
     where
-        S: Into<RcString>,
+        S: Into<JsString>,
     {
         Self {
             data: ObjectData::String(value.into()),
@@ -413,7 +413,7 @@ impl Object {
     }
 
     #[inline]
-    pub fn as_string(&self) -> Option<RcString> {
+    pub fn as_string(&self) -> Option<JsString> {
         match self.data {
             ObjectData::String(ref string) => Some(string.clone()),
             _ => None,
@@ -628,13 +628,13 @@ impl Object {
 #[derive(Debug, Clone)]
 pub struct FunctionBinding {
     binding: PropertyKey,
-    name: RcString,
+    name: JsString,
 }
 
 impl From<&str> for FunctionBinding {
     #[inline]
     fn from(name: &str) -> Self {
-        let name: RcString = name.into();
+        let name: JsString = name.into();
 
         Self {
             binding: name.clone().into(),
@@ -646,7 +646,7 @@ impl From<&str> for FunctionBinding {
 impl From<String> for FunctionBinding {
     #[inline]
     fn from(name: String) -> Self {
-        let name: RcString = name.into();
+        let name: JsString = name.into();
 
         Self {
             binding: name.clone().into(),
@@ -655,9 +655,9 @@ impl From<String> for FunctionBinding {
     }
 }
 
-impl From<RcString> for FunctionBinding {
+impl From<JsString> for FunctionBinding {
     #[inline]
-    fn from(name: RcString) -> Self {
+    fn from(name: JsString) -> Self {
         Self {
             binding: name.clone().into(),
             name,
diff --git a/boa/src/property/mod.rs b/boa/src/property/mod.rs
index bd3a8891915..b5411c6645d 100644
--- a/boa/src/property/mod.rs
+++ b/boa/src/property/mod.rs
@@ -17,8 +17,7 @@
 use crate::{
     gc::{Finalize, Trace},
     object::GcObject,
-    value::{RcString, Value},
-    JsSymbol,
+    JsString, JsSymbol, Value,
 };
 use std::{convert::TryFrom, fmt};
 
@@ -306,14 +305,14 @@ impl PropertyDescriptor {
 /// [spec]: https://tc39.es/ecma262/#sec-ispropertykey
 #[derive(Trace, Finalize, Debug, Clone)]
 pub enum PropertyKey {
-    String(RcString),
+    String(JsString),
     Symbol(JsSymbol),
     Index(u32),
 }
 
-impl From<RcString> for PropertyKey {
+impl From<JsString> for PropertyKey {
     #[inline]
-    fn from(string: RcString) -> PropertyKey {
+    fn from(string: JsString) -> PropertyKey {
         if let Ok(index) = string.parse() {
             PropertyKey::Index(index)
         } else {
@@ -430,7 +429,7 @@ impl From<usize> for PropertyKey {
         if let Ok(index) = u32::try_from(value) {
             PropertyKey::Index(index)
         } else {
-            PropertyKey::String(RcString::from(value.to_string()))
+            PropertyKey::String(JsString::from(value.to_string()))
         }
     }
 }
@@ -440,7 +439,7 @@ impl From<isize> for PropertyKey {
         if let Ok(index) = u32::try_from(value) {
             PropertyKey::Index(index)
         } else {
-            PropertyKey::String(RcString::from(value.to_string()))
+            PropertyKey::String(JsString::from(value.to_string()))
         }
     }
 }
@@ -450,7 +449,7 @@ impl From<i32> for PropertyKey {
         if let Ok(index) = u32::try_from(value) {
             PropertyKey::Index(index)
         } else {
-            PropertyKey::String(RcString::from(value.to_string()))
+            PropertyKey::String(JsString::from(value.to_string()))
         }
     }
 }
diff --git a/boa/src/string.rs b/boa/src/string.rs
new file mode 100644
index 00000000000..60cfc50dc6c
--- /dev/null
+++ b/boa/src/string.rs
@@ -0,0 +1,448 @@
+use crate::gc::{empty_trace, Finalize, Trace};
+use std::{
+    alloc::{alloc, dealloc, Layout},
+    borrow::Borrow,
+    cell::Cell,
+    hash::{Hash, Hasher},
+    marker::PhantomData,
+    ops::Deref,
+    ptr::{copy_nonoverlapping, NonNull},
+};
+
+/// The inner representation of a [`JsString`].
+#[repr(C)]
+struct Inner {
+    /// The utf8 length, the number of bytes.
+    len: usize,
+
+    /// The number of references to the string.
+    ///
+    /// When this reaches `0` the string is deallocated.
+    refcount: Cell<usize>,
+
+    /// An empty array which is used to get the offset of string data.
+    data: [u8; 0],
+}
+
+impl Inner {
+    /// Create a new `Inner` from `&str`.
+    #[inline]
+    fn new(s: &str) -> NonNull<Self> {
+        // We get the layout of the `Inner` type and we extend by the size
+        // of the string array.
+        let inner_layout = Layout::new::<Inner>();
+        let (layout, offset) = inner_layout
+            .extend(Layout::array::<u8>(s.len()).unwrap())
+            .unwrap();
+
+        let inner = unsafe {
+            let inner = alloc(layout) as *mut Inner;
+
+            // Write the first part, the Inner.
+            inner.write(Inner {
+                len: s.len(),
+                refcount: Cell::new(1),
+                data: [0; 0],
+            });
+
+            // Get offset into the string data.
+            let data = (*inner).data.as_mut_ptr();
+
+            debug_assert!(std::ptr::eq(inner.cast::<u8>().add(offset), data));
+
+            // Copy string data into data offset.
+            copy_nonoverlapping(s.as_ptr(), data, s.len());
+
+            inner
+        };
+
+        // Safety: We already know it's not null, so this is safe.
+        unsafe { NonNull::new_unchecked(inner) }
+    }
+
+    /// Concatinate two string.
+    #[inline]
+    fn concat(x: &str, y: &str) -> NonNull<Inner> {
+        let total_string_size = x.len() + y.len();
+
+        // We get the layout of the `Inner` type and we extend by the size
+        // of the string array.
+        let inner_layout = Layout::new::<Inner>();
+        let (layout, offset) = inner_layout
+            .extend(Layout::array::<u8>(total_string_size).unwrap())
+            .unwrap();
+
+        let inner = unsafe {
+            let inner = alloc(layout) as *mut Inner;
+
+            // Write the first part, the Inner.
+            inner.write(Inner {
+                len: total_string_size,
+                refcount: Cell::new(1),
+                data: [0; 0],
+            });
+
+            // Get offset into the string data.
+            let data = (*inner).data.as_mut_ptr();
+
+            debug_assert!(std::ptr::eq(inner.cast::<u8>().add(offset), data));
+
+            // Copy the two string data into data offset.
+            copy_nonoverlapping(x.as_ptr(), data, x.len());
+            copy_nonoverlapping(y.as_ptr(), data.add(x.len()), y.len());
+
+            inner
+        };
+
+        // Safety: We already know it's not null, so this is safe.
+        unsafe { NonNull::new_unchecked(inner) }
+    }
+
+    /// Deallocate inner type with string data.
+    #[inline]
+    unsafe fn dealloc(x: NonNull<Inner>) {
+        let len = (*x.as_ptr()).len;
+
+        let inner_layout = Layout::new::<Inner>();
+        let (layout, _offset) = inner_layout
+            .extend(Layout::array::<u8>(len).unwrap())
+            .unwrap();
+
+        dealloc(x.as_ptr() as _, layout);
+    }
+}
+
+/// This represents a JavaScript primitive string.
+///
+/// This is similar to `Rc<str>`. But unlike `Rc<str>` which stores the length
+/// on the stack and a pointer to the data (this is also known as fat pointers).
+/// The `JsString` length and data is stored on the heap. and just an non-null
+/// pointer is kept, so its size is the size of a pointer.
+pub struct JsString {
+    inner: NonNull<Inner>,
+    _marker: PhantomData<std::rc::Rc<str>>,
+}
+
+impl Default for JsString {
+    #[inline]
+    fn default() -> Self {
+        Self::new("")
+    }
+}
+
+impl JsString {
+    /// Create a new JavaScript string.
+    #[inline]
+    pub fn new<S: AsRef<str>>(s: S) -> Self {
+        let s = s.as_ref();
+        Self {
+            inner: Inner::new(s),
+            _marker: PhantomData,
+        }
+    }
+
+    /// Concatinate two string.
+    pub fn concat<T, U>(x: T, y: U) -> JsString
+    where
+        T: AsRef<str>,
+        U: AsRef<str>,
+    {
+        let x = x.as_ref();
+        let y = y.as_ref();
+
+        Self {
+            inner: Inner::concat(x, y),
+            _marker: PhantomData,
+        }
+    }
+
+    /// Return the inner representation.
+    #[inline]
+    fn inner(&self) -> &Inner {
+        unsafe { self.inner.as_ref() }
+    }
+
+    /// Return the JavaScript string as a rust `&str`.
+    #[inline]
+    pub fn as_str(&self) -> &str {
+        let inner = self.inner();
+
+        unsafe {
+            let slice = std::slice::from_raw_parts(inner.data.as_ptr(), inner.len);
+            std::str::from_utf8_unchecked(slice)
+        }
+    }
+
+    /// Gets the number of `JsString`s which point to this allocation.
+    #[inline]
+    pub fn refcount(this: &Self) -> usize {
+        this.inner().refcount.get()
+    }
+
+    /// Returns `true` if the two `JsString`s point to the same allocation (in a vein similar to [`ptr::eq`]).
+    ///
+    /// [`ptr::eq`]: std::ptr::eq
+    #[inline]
+    pub fn ptr_eq(x: &Self, y: &Self) -> bool {
+        x.inner == y.inner
+    }
+}
+
+impl Finalize for JsString {}
+
+// Safety: [`JsString`] does not contain any objects which recquire trace,
+// so this is safe.
+unsafe impl Trace for JsString {
+    empty_trace!();
+}
+
+impl Clone for JsString {
+    #[inline]
+    fn clone(&self) -> Self {
+        let inner = self.inner();
+        inner.refcount.set(inner.refcount.get() + 1);
+
+        JsString {
+            inner: self.inner,
+            _marker: PhantomData,
+        }
+    }
+}
+
+impl Drop for JsString {
+    #[inline]
+    fn drop(&mut self) {
+        let inner = self.inner();
+        if inner.refcount.get() == 1 {
+            // Safety: If refcount is 1 and we call drop, that means this is the last
+            // JsString which points to this memory allocation, so deallocating it is safe.
+            unsafe {
+                Inner::dealloc(self.inner);
+            }
+        } else {
+            inner.refcount.set(inner.refcount.get() - 1);
+        }
+    }
+}
+
+impl std::fmt::Debug for JsString {
+    #[inline]
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.as_str().fmt(f)
+    }
+}
+
+impl std::fmt::Display for JsString {
+    #[inline]
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.as_str().fmt(f)
+    }
+}
+
+impl From<&str> for JsString {
+    #[inline]
+    fn from(s: &str) -> Self {
+        Self::new(s)
+    }
+}
+
+impl From<Box<str>> for JsString {
+    #[inline]
+    fn from(s: Box<str>) -> Self {
+        Self::new(s)
+    }
+}
+
+impl From<String> for JsString {
+    #[inline]
+    fn from(s: String) -> Self {
+        Self::new(s)
+    }
+}
+
+impl AsRef<str> for JsString {
+    #[inline]
+    fn as_ref(&self) -> &str {
+        self.as_str()
+    }
+}
+
+impl Borrow<str> for JsString {
+    #[inline]
+    fn borrow(&self) -> &str {
+        self.as_str()
+    }
+}
+
+impl Deref for JsString {
+    type Target = str;
+
+    #[inline]
+    fn deref(&self) -> &Self::Target {
+        self.as_str()
+    }
+}
+
+impl PartialEq<JsString> for JsString {
+    #[inline]
+    fn eq(&self, other: &Self) -> bool {
+        // If they point at the same memory allocation, then they are equal.
+        if Self::ptr_eq(self, other) {
+            return true;
+        }
+
+        self.as_str() == other.as_str()
+    }
+}
+
+impl Eq for JsString {}
+
+impl Hash for JsString {
+    #[inline]
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.as_str().hash(state);
+    }
+}
+
+impl PartialOrd for JsString {
+    #[inline]
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        self.as_str().partial_cmp(other)
+    }
+}
+
+impl Ord for JsString {
+    #[inline]
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        self.as_str().cmp(other)
+    }
+}
+
+impl PartialEq<str> for JsString {
+    #[inline]
+    fn eq(&self, other: &str) -> bool {
+        self.as_str() == other
+    }
+}
+
+impl PartialEq<JsString> for str {
+    #[inline]
+    fn eq(&self, other: &JsString) -> bool {
+        self == other.as_str()
+    }
+}
+
+impl PartialEq<&str> for JsString {
+    #[inline]
+    fn eq(&self, other: &&str) -> bool {
+        self.as_str() == *other
+    }
+}
+
+impl PartialEq<JsString> for &str {
+    #[inline]
+    fn eq(&self, other: &JsString) -> bool {
+        *self == other.as_str()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::JsString;
+    use std::mem::size_of;
+
+    #[test]
+    fn empty() {
+        let _ = JsString::new("");
+    }
+
+    #[test]
+    fn pointer_size() {
+        assert_eq!(size_of::<JsString>(), size_of::<*const u8>());
+        assert_eq!(size_of::<Option<JsString>>(), size_of::<*const u8>());
+    }
+
+    #[test]
+    fn refcount() {
+        let x = JsString::new("Hello wrold");
+        assert_eq!(JsString::refcount(&x), 1);
+
+        {
+            let y = x.clone();
+            assert_eq!(JsString::refcount(&x), 2);
+            assert_eq!(JsString::refcount(&y), 2);
+
+            {
+                let z = y.clone();
+                assert_eq!(JsString::refcount(&x), 3);
+                assert_eq!(JsString::refcount(&y), 3);
+                assert_eq!(JsString::refcount(&z), 3);
+            }
+
+            assert_eq!(JsString::refcount(&x), 2);
+            assert_eq!(JsString::refcount(&y), 2);
+        }
+
+        assert_eq!(JsString::refcount(&x), 1);
+    }
+
+    #[test]
+    fn ptr_eq() {
+        let x = JsString::new("Hello");
+        let y = x.clone();
+
+        assert!(JsString::ptr_eq(&x, &y));
+
+        let z = JsString::new("Hello");
+        assert!(!JsString::ptr_eq(&x, &z));
+        assert!(!JsString::ptr_eq(&y, &z));
+    }
+
+    #[test]
+    fn as_str() {
+        let s = "Hello";
+        let x = JsString::new(s);
+
+        assert_eq!(x.as_str(), s);
+    }
+
+    #[test]
+    fn hash() {
+        use std::collections::hash_map::DefaultHasher;
+        use std::hash::{Hash, Hasher};
+
+        let s = "Hello, world!";
+        let x = JsString::new(s);
+
+        assert_eq!(x.as_str(), s);
+
+        let mut hasher = DefaultHasher::new();
+        s.hash(&mut hasher);
+        let s_hash = hasher.finish();
+        let mut hasher = DefaultHasher::new();
+        x.hash(&mut hasher);
+        let x_hash = hasher.finish();
+
+        assert_eq!(s_hash, x_hash);
+    }
+
+    #[test]
+    fn concat() {
+        let x = JsString::new("hello");
+        let y = ", ";
+        let z = JsString::new("world");
+        let w = String::from("!");
+
+        let xy = JsString::concat(x, y);
+        assert_eq!(xy, "hello, ");
+        assert_eq!(JsString::refcount(&xy), 1);
+
+        let xyz = JsString::concat(xy, z);
+        assert_eq!(xyz, "hello, world");
+        assert_eq!(JsString::refcount(&xyz), 1);
+
+        let xyzw = JsString::concat(xyz, w);
+        assert_eq!(xyzw, "hello, world!");
+        assert_eq!(JsString::refcount(&xyzw), 1);
+    }
+}
diff --git a/boa/src/symbol.rs b/boa/src/symbol.rs
index 353dee4dd98..e35f154dcee 100644
--- a/boa/src/symbol.rs
+++ b/boa/src/symbol.rs
@@ -17,7 +17,7 @@
 
 use crate::{
     gc::{empty_trace, Finalize, Trace},
-    value::RcString,
+    JsString,
 };
 use std::{
     cell::Cell,
@@ -246,7 +246,7 @@ impl WellKnownSymbols {
 #[derive(Debug, Clone)]
 struct Inner {
     hash: u64,
-    description: Option<RcString>,
+    description: Option<JsString>,
 }
 
 /// This represents a JavaScript symbol primitive.
@@ -258,7 +258,7 @@ pub struct JsSymbol {
 impl JsSymbol {
     /// Create a new symbol.
     #[inline]
-    pub fn new(description: Option<RcString>) -> Self {
+    pub fn new(description: Option<JsString>) -> Self {
         let hash = SYMBOL_HASH_COUNT.with(|count| {
             let hash = count.get();
             count.set(hash + 1);
@@ -272,7 +272,7 @@ impl JsSymbol {
 
     /// Create a new symbol with a specified hash and description.
     #[inline]
-    fn with_hash(hash: u64, description: Option<RcString>) -> Self {
+    fn with_hash(hash: u64, description: Option<JsString>) -> Self {
         Self {
             inner: Rc::new(Inner { hash, description }),
         }
@@ -280,7 +280,7 @@ impl JsSymbol {
 
     /// Returns the `Symbol`s description.
     #[inline]
-    pub fn description(&self) -> Option<RcString> {
+    pub fn description(&self) -> Option<JsString> {
         self.inner.description.clone()
     }
 
diff --git a/boa/src/value/conversions.rs b/boa/src/value/conversions.rs
index b920242ff28..13107ddfdf8 100644
--- a/boa/src/value/conversions.rs
+++ b/boa/src/value/conversions.rs
@@ -44,9 +44,9 @@ impl From<char> for Value {
     }
 }
 
-impl From<RcString> for Value {
+impl From<JsString> for Value {
     #[inline]
-    fn from(value: RcString) -> Self {
+    fn from(value: JsString) -> Self {
         Value::String(value)
     }
 }
diff --git a/boa/src/value/mod.rs b/boa/src/value/mod.rs
index 9708e0f1a18..8bdfc4dfa66 100644
--- a/boa/src/value/mod.rs
+++ b/boa/src/value/mod.rs
@@ -14,7 +14,7 @@ use crate::{
     object::{GcObject, Object, ObjectData},
     property::{Attribute, DataDescriptor, PropertyDescriptor, PropertyKey},
     symbol::{JsSymbol, WellKnownSymbols},
-    BoaProfiler, Context, Result,
+    BoaProfiler, Context, JsString, Result,
 };
 use gc::{Finalize, Trace};
 use serde_json::{Number as JSONNumber, Value as JSONValue};
@@ -31,7 +31,6 @@ mod equality;
 mod hash;
 mod operations;
 mod rcbigint;
-mod rcstring;
 mod r#type;
 
 pub use conversions::*;
@@ -41,7 +40,6 @@ pub use hash::*;
 pub use operations::*;
 pub use r#type::Type;
 pub use rcbigint::RcBigInt;
-pub use rcstring::RcString;
 
 /// A Javascript value
 #[derive(Trace, Finalize, Debug, Clone)]
@@ -53,7 +51,7 @@ pub enum Value {
     /// `boolean` - A `true` / `false` value, for if a certain criteria is met.
     Boolean(bool),
     /// `String` - A UTF-8 string, such as `"Hello, world"`.
-    String(RcString),
+    String(JsString),
     /// `Number` - A 64-bit floating point number, such as `3.1415`
     Rational(f64),
     /// `Number` - A 32-bit integer, such as `42`.
@@ -109,7 +107,7 @@ impl Value {
     #[inline]
     pub fn string<S>(value: S) -> Self
     where
-        S: Into<RcString>,
+        S: Into<JsString>,
     {
         Self::String(value.into())
     }
@@ -368,7 +366,7 @@ impl Value {
 
     /// Returns the string if the values is a string, otherwise `None`.
     #[inline]
-    pub fn as_string(&self) -> Option<&RcString> {
+    pub fn as_string(&self) -> Option<&JsString> {
         match self {
             Self::String(ref string) => Some(string),
             _ => None,
@@ -643,7 +641,7 @@ impl Value {
     /// Converts the value to a string.
     ///
     /// This function is equivalent to `String(value)` in JavaScript.
-    pub fn to_string(&self, context: &mut Context) -> Result<RcString> {
+    pub fn to_string(&self, context: &mut Context) -> Result<JsString> {
         match self {
             Value::Null => Ok("null".into()),
             Value::Undefined => Ok("undefined".into()),
diff --git a/boa/src/value/operations.rs b/boa/src/value/operations.rs
index 7067bc075e8..cbd30172e2f 100644
--- a/boa/src/value/operations.rs
+++ b/boa/src/value/operations.rs
@@ -11,9 +11,9 @@ impl Value {
             (Self::Integer(x), Self::Rational(y)) => Self::rational(f64::from(*x) + y),
             (Self::Rational(x), Self::Integer(y)) => Self::rational(x + f64::from(*y)),
 
-            (Self::String(ref x), Self::String(ref y)) => Self::string(format!("{}{}", x, y)),
-            (Self::String(ref x), ref y) => Self::string(format!("{}{}", x, y.to_string(context)?)),
-            (ref x, Self::String(ref y)) => Self::string(format!("{}{}", x.to_string(context)?, y)),
+            (Self::String(ref x), Self::String(ref y)) => Self::from(JsString::concat(x, y)),
+            (Self::String(ref x), ref y) => Self::from(JsString::concat(x, y.to_string(context)?)),
+            (ref x, Self::String(ref y)) => Self::from(JsString::concat(x.to_string(context)?, y)),
             (Self::BigInt(ref n1), Self::BigInt(ref n2)) => {
                 Self::bigint(n1.as_inner().clone() + n2.as_inner().clone())
             }
@@ -24,10 +24,10 @@ impl Value {
                 other.to_primitive(context, PreferredType::Default)?,
             ) {
                 (Self::String(ref x), ref y) => {
-                    Self::string(format!("{}{}", x, y.to_string(context)?))
+                    Self::from(JsString::concat(x, y.to_string(context)?))
                 }
                 (ref x, Self::String(ref y)) => {
-                    Self::string(format!("{}{}", x.to_string(context)?, y))
+                    Self::from(JsString::concat(x.to_string(context)?, y))
                 }
                 (x, y) => match (x.to_numeric(context)?, y.to_numeric(context)?) {
                     (Numeric::Number(x), Numeric::Number(y)) => Self::rational(x + y),
diff --git a/boa/src/value/rcstring.rs b/boa/src/value/rcstring.rs
deleted file mode 100644
index 987d7a7a394..00000000000
--- a/boa/src/value/rcstring.rs
+++ /dev/null
@@ -1,114 +0,0 @@
-use crate::gc::{empty_trace, Finalize, Trace};
-
-use std::{
-    borrow::Borrow,
-    fmt::{self, Display},
-    ops::Deref,
-    rc::Rc,
-};
-
-#[derive(Debug, Finalize, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct RcString(Rc<str>);
-
-unsafe impl Trace for RcString {
-    empty_trace!();
-}
-
-impl RcString {
-    #[inline]
-    pub fn as_str(&self) -> &str {
-        &self.0
-    }
-}
-
-impl Default for RcString {
-    #[inline]
-    fn default() -> Self {
-        Self(Rc::from(String::new()))
-    }
-}
-
-impl Display for RcString {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        Display::fmt(&self.0, f)
-    }
-}
-
-impl PartialEq<str> for RcString {
-    #[inline]
-    fn eq(&self, other: &str) -> bool {
-        self.as_str() == other
-    }
-}
-
-impl PartialEq<RcString> for str {
-    #[inline]
-    fn eq(&self, other: &RcString) -> bool {
-        self == other.as_str()
-    }
-}
-
-impl PartialEq<&str> for RcString {
-    #[inline]
-    fn eq(&self, other: &&str) -> bool {
-        self.as_str() == *other
-    }
-}
-
-impl PartialEq<RcString> for &str {
-    #[inline]
-    fn eq(&self, other: &RcString) -> bool {
-        *self == other.as_str()
-    }
-}
-
-impl Deref for RcString {
-    type Target = str;
-
-    #[inline]
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
-}
-
-impl Borrow<str> for RcString {
-    #[inline]
-    fn borrow(&self) -> &str {
-        self.0.borrow()
-    }
-}
-
-impl AsRef<str> for RcString {
-    #[inline]
-    fn as_ref(&self) -> &str {
-        self.as_str()
-    }
-}
-
-impl From<String> for RcString {
-    #[inline]
-    fn from(string: String) -> Self {
-        Self(Rc::from(string))
-    }
-}
-
-impl From<&RcString> for String {
-    #[inline]
-    fn from(string: &RcString) -> Self {
-        string.to_string()
-    }
-}
-
-impl From<Box<str>> for RcString {
-    #[inline]
-    fn from(string: Box<str>) -> Self {
-        Self(Rc::from(string))
-    }
-}
-
-impl From<&str> for RcString {
-    #[inline]
-    fn from(string: &str) -> Self {
-        Self(Rc::from(string))
-    }
-}
diff --git a/boa/src/vm/code_block.rs b/boa/src/vm/code_block.rs
index 8f6e51a6c53..d3eb4bb8dbf 100644
--- a/boa/src/vm/code_block.rs
+++ b/boa/src/vm/code_block.rs
@@ -1,4 +1,4 @@
-use crate::{value::RcString, vm::Opcode, Value};
+use crate::{vm::Opcode, JsString, Value};
 
 use std::{convert::TryInto, fmt::Write, mem::size_of};
 
@@ -25,7 +25,7 @@ pub struct CodeBlock {
     pub(crate) literals: Vec<Value>,
 
     /// Variables names
-    pub(crate) names: Vec<RcString>,
+    pub(crate) names: Vec<JsString>,
 }
 
 impl Default for CodeBlock {