diff --git a/runtime/mlBytes.js b/runtime/mlBytes.js
index fe7e7f9c3d..61ca734ba3 100644
--- a/runtime/mlBytes.js
+++ b/runtime/mlBytes.js
@@ -82,115 +82,6 @@ function caml_subarray_to_jsbytes(a, i, len) {
   return s;
 }
 
-//Provides: caml_utf8_of_utf16
-function caml_utf8_of_utf16(s) {
-  for (var b = "", t = b, c, d, i = 0, l = s.length; i < l; i++) {
-    c = s.charCodeAt(i);
-    if (c < 0x80) {
-      for (var j = i + 1; j < l && (c = s.charCodeAt(j)) < 0x80; j++);
-      if (j - i > 512) {
-        t.slice(0, 1);
-        b += t;
-        t = "";
-        b += s.slice(i, j);
-      } else t += s.slice(i, j);
-      if (j === l) break;
-      i = j;
-    }
-    if (c < 0x800) {
-      t += String.fromCharCode(0xc0 | (c >> 6));
-      t += String.fromCharCode(0x80 | (c & 0x3f));
-    } else if (c < 0xd800 || c >= 0xdfff) {
-      t += String.fromCharCode(
-        0xe0 | (c >> 12),
-        0x80 | ((c >> 6) & 0x3f),
-        0x80 | (c & 0x3f),
-      );
-    } else if (
-      c >= 0xdbff ||
-      i + 1 === l ||
-      (d = s.charCodeAt(i + 1)) < 0xdc00 ||
-      d > 0xdfff
-    ) {
-      // Unmatched surrogate pair, replaced by \ufffd (replacement character)
-      t += "\xef\xbf\xbd";
-    } else {
-      i++;
-      c = (c << 10) + d - 0x35fdc00;
-      t += String.fromCharCode(
-        0xf0 | (c >> 18),
-        0x80 | ((c >> 12) & 0x3f),
-        0x80 | ((c >> 6) & 0x3f),
-        0x80 | (c & 0x3f),
-      );
-    }
-    if (t.length > 1024) {
-      t.slice(0, 1);
-      b += t;
-      t = "";
-    }
-  }
-  return b + t;
-}
-
-//Provides: caml_utf16_of_utf8
-function caml_utf16_of_utf8(s) {
-  for (var b = "", t = "", c, c1, c2, v, i = 0, l = s.length; i < l; i++) {
-    c1 = s.charCodeAt(i);
-    if (c1 < 0x80) {
-      for (var j = i + 1; j < l && (c1 = s.charCodeAt(j)) < 0x80; j++);
-      if (j - i > 512) {
-        t.slice(0, 1);
-        b += t;
-        t = "";
-        b += s.slice(i, j);
-      } else t += s.slice(i, j);
-      if (j === l) break;
-      i = j;
-    }
-    v = 1;
-    if (++i < l && ((c2 = s.charCodeAt(i)) & -64) === 128) {
-      c = c2 + (c1 << 6);
-      if (c1 < 0xe0) {
-        v = c - 0x3080;
-        if (v < 0x80) v = 1;
-      } else {
-        v = 2;
-        if (++i < l && ((c2 = s.charCodeAt(i)) & -64) === 128) {
-          c = c2 + (c << 6);
-          if (c1 < 0xf0) {
-            v = c - 0xe2080;
-            if (v < 0x800 || (v >= 0xd7ff && v < 0xe000)) v = 2;
-          } else {
-            v = 3;
-            if (
-              ++i < l &&
-              ((c2 = s.charCodeAt(i)) & -64) === 128 &&
-              c1 < 0xf5
-            ) {
-              v = c2 - 0x3c82080 + (c << 6);
-              if (v < 0x10000 || v > 0x10ffff) v = 3;
-            }
-          }
-        }
-      }
-    }
-    if (v < 4) {
-      // Invalid sequence
-      i -= v;
-      t += "\ufffd";
-    } else if (v > 0xffff)
-      t += String.fromCharCode(0xd7c0 + (v >> 10), 0xdc00 + (v & 0x3ff));
-    else t += String.fromCharCode(v);
-    if (t.length > 1024) {
-      t.slice(0, 1);
-      b += t;
-      t = "";
-    }
-  }
-  return b + t;
-}
-
 //Provides: jsoo_is_ascii
 function jsoo_is_ascii(s) {
   // The regular expression gets better at around this point for all browsers
@@ -429,17 +320,29 @@ function caml_bytes_set(s, i, c) {
   return caml_bytes_unsafe_set(s, i, c);
 }
 
+//Provides: jsoo_text_encoder
+var jsoo_text_encoder = new TextEncoder();
+
+//Provides: jsoo_text_decoder
+var jsoo_text_decoder = new TextDecoder();
+
 //Provides: caml_bytes_of_utf16_jsstring
-//Requires: jsoo_is_ascii, caml_utf8_of_utf16, MlBytes
+//Requires: MlBytes, jsoo_text_encoder
+//Requires: jsoo_is_ascii
 function caml_bytes_of_utf16_jsstring(s) {
-  var tag = 9 /* BYTES | ASCII */;
-  if (!jsoo_is_ascii(s))
-    (tag = 8) /* BYTES | NOT_ASCII */, (s = caml_utf8_of_utf16(s));
-  return new MlBytes(tag, s, s.length);
+  if(jsoo_is_ascii(s)){
+    return new MlBytes(9, s, s.length)
+  }
+  else {
+    var a = jsoo_text_encoder.encode(s);
+    return new MlBytes(4, a, a.length);
+  }
 }
 
 //Provides: MlBytes
-//Requires: caml_convert_string_to_bytes, jsoo_is_ascii, caml_utf16_of_utf8
+//Requires: caml_convert_string_to_bytes, jsoo_is_ascii
+//Requires: caml_uint8_array_of_bytes
+//Requires: jsoo_text_decoder
 function MlBytes(tag, contents, length) {
   this.t = tag;
   this.c = contents;
@@ -462,9 +365,9 @@ MlBytes.prototype.toString = function () {
   }
 };
 MlBytes.prototype.toUtf16 = function () {
-  var r = this.toString();
-  if (this.t === 9) return r;
-  return caml_utf16_of_utf8(r);
+  if (this.t === 9) return this.c;
+  var a = caml_uint8_array_of_bytes(this);
+  return jsoo_text_decoder.decode(a);
 };
 MlBytes.prototype.slice = function () {
   var content = this.t === 4 ? this.c.slice() : this.c;
@@ -777,20 +680,35 @@ function caml_jsbytes_of_string(x) {
   return x;
 }
 
+//Provides: jsoo_text_decoder_buff
+var jsoo_text_decoder_buff = new ArrayBuffer(1024);
+
 //Provides: caml_jsstring_of_string const
-//Requires: jsoo_is_ascii, caml_utf16_of_utf8
+//Requires: jsoo_is_ascii
+//Requires: jsoo_text_decoder
+//Requires: jsoo_text_decoder_buff
 //If: js-string
 function caml_jsstring_of_string(s) {
   if (jsoo_is_ascii(s)) return s;
-  return caml_utf16_of_utf8(s);
+  var a =
+    s.length <= jsoo_text_decoder_buff.length
+      ? new Uint8Array(jsoo_text_decoder_buff, 0, s.length)
+      : new Uint8Array(s.length);
+  for (var i = 0; i < s.length; i++) {
+    a[i] = s.charCodeAt(i);
+  }
+  return jsoo_text_decoder.decode(a);
 }
 
 //Provides: caml_string_of_jsstring const
-//Requires: jsoo_is_ascii, caml_utf8_of_utf16, caml_string_of_jsbytes
+//Requires: caml_string_of_array
+//Requires: jsoo_text_encoder
+//Requires: jsoo_is_ascii, caml_string_of_jsbytes
 //If: js-string
 function caml_string_of_jsstring(s) {
-  if (jsoo_is_ascii(s)) return caml_string_of_jsbytes(s);
-  else return caml_string_of_jsbytes(caml_utf8_of_utf16(s));
+  if(jsoo_is_ascii(s)) return caml_string_of_jsbytes(s);
+  var a = jsoo_text_encoder.encode(s);
+  return caml_string_of_array(a);
 }
 
 //Provides: caml_bytes_of_jsbytes const
@@ -910,7 +828,6 @@ function caml_ml_bytes_content(s) {
 }
 
 //Provides: caml_is_ml_string
-//Requires: jsoo_is_ascii
 //If: js-string
 function caml_is_ml_string(s) {
   // biome-ignore lint/suspicious/noControlCharactersInRegex: expected