diff --git a/sdk/src/Core/AWSSDK.Core.NetFramework.csproj b/sdk/src/Core/AWSSDK.Core.NetFramework.csproj
index 3d740253846d..0c065257520a 100644
--- a/sdk/src/Core/AWSSDK.Core.NetFramework.csproj
+++ b/sdk/src/Core/AWSSDK.Core.NetFramework.csproj
@@ -21,6 +21,8 @@
     <NoWarn>$(NoWarn);CS1591</NoWarn>
 
     <SignAssembly>True</SignAssembly>
+
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <PropertyGroup Condition=" '$(RuleSetFileForBuild)' == 'false' Or '$(RuleSetFileForBuild)' == '' ">
diff --git a/sdk/src/Core/AWSSDK.Core.NetStandard.csproj b/sdk/src/Core/AWSSDK.Core.NetStandard.csproj
index ca3d2cd81cb8..2e9e23b042d0 100644
--- a/sdk/src/Core/AWSSDK.Core.NetStandard.csproj
+++ b/sdk/src/Core/AWSSDK.Core.NetStandard.csproj
@@ -21,8 +21,8 @@
     <GenerateAssemblyDescriptionAttribute>false</GenerateAssemblyDescriptionAttribute>
 
     <NoWarn>$(NoWarn);CS1591;CA1822</NoWarn>
-	  <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
-	  <SignAssembly>True</SignAssembly>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <SignAssembly>True</SignAssembly>
 
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
diff --git a/sdk/src/Core/Amazon.Runtime/Internal/MissingTypes/SkipLocalsInitAttribute.cs b/sdk/src/Core/Amazon.Runtime/Internal/MissingTypes/SkipLocalsInitAttribute.cs
new file mode 100644
index 000000000000..dce5b822e352
--- /dev/null
+++ b/sdk/src/Core/Amazon.Runtime/Internal/MissingTypes/SkipLocalsInitAttribute.cs
@@ -0,0 +1,10 @@
+#if !NET8_0_OR_GREATER
+namespace System.Runtime.CompilerServices
+{
+    /// <summary>Indicates to the compiler that the .locals init flag should not be set in nested method headers when emitting to metadata.</summary>
+    [AttributeUsage(AttributeTargets.Module | AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Constructor | AttributeTargets.Method | AttributeTargets.Property | AttributeTargets.Event | AttributeTargets.Interface, Inherited = false)]
+    internal sealed class SkipLocalsInitAttribute : Attribute
+    {
+    }
+}
+#endif
\ No newline at end of file
diff --git a/sdk/src/Core/Amazon.Util/AWSSDKUtils.cs b/sdk/src/Core/Amazon.Util/AWSSDKUtils.cs
index 5bce4abb050a..64ae04b6fd07 100644
--- a/sdk/src/Core/Amazon.Util/AWSSDKUtils.cs
+++ b/sdk/src/Core/Amazon.Util/AWSSDKUtils.cs
@@ -33,6 +33,7 @@
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
+using System.Runtime.CompilerServices;
 using System.Threading;
 using Amazon.Runtime.Endpoints;
 using ThirdParty.RuntimeBackports;
@@ -79,12 +80,6 @@ public static partial class AWSSDKUtils
         // Default value of progress update interval for streaming is 100KB.
         public const long DefaultProgressUpdateInterval = 102400;
 
-        internal static Dictionary<int, string> RFCEncodingSchemes = new Dictionary<int, string>
-        {
-            { 3986,  ValidUrlCharacters },
-            { 1738,  ValidUrlCharactersRFC1738 }
-        };
-
         internal const string S3Accelerate = "s3-accelerate";
         internal const string S3Control = "s3-control";
 
@@ -1028,35 +1023,76 @@ public static string UrlEncode(string data, bool path)
         /// Currently recognised RFC versions are 1738 (Dec '94) and 3986 (Jan '05). 
         /// If the specified RFC is not recognised, 3986 is used by default.
         /// </remarks>
+        [SkipLocalsInit]
         public static string UrlEncode(int rfcNumber, string data, bool path)
         {
-            StringBuilder encoded = new StringBuilder(data.Length * 2);
-            string validUrlCharacters;
-            if (!RFCEncodingSchemes.TryGetValue(rfcNumber, out validUrlCharacters))
-                validUrlCharacters = ValidUrlCharacters;
-
-            string unreservedChars = String.Concat(validUrlCharacters, (path ? ValidPathCharacters : ""));
-            foreach (char symbol in System.Text.Encoding.UTF8.GetBytes(data))
+            byte[] sharedDataBuffer = null;
+            const int MaxStackLimit = 256;
+            try
             {
-                if (unreservedChars.IndexOf(symbol) != -1)
-                {
-                    encoded.Append(symbol);
-                }
-                else
+                if (!TryGetRFCEncodingSchemes(rfcNumber, out var validUrlCharacters))
+                    validUrlCharacters = ValidUrlCharacters;
+
+                var unreservedChars = string.Concat(validUrlCharacters, path ? ValidPathCharacters : string.Empty).AsSpan();
+
+                var dataAsSpan = data.AsSpan();
+                var encoding = Encoding.UTF8;
+
+                var dataByteLength = encoding.GetMaxByteCount(dataAsSpan.Length);
+                var encodedByteLength = 2 * dataByteLength;
+                var dataBuffer = encodedByteLength <= MaxStackLimit
+                    ? stackalloc byte[MaxStackLimit]
+                    : sharedDataBuffer = ArrayPool<byte>.Shared.Rent(encodedByteLength);
+                // Instead of stack allocating or renting two buffers we use one buffer with at least twice the capacity of the
+                // max encoding length. Then store the character data as bytes in the second half reserving the first half of the buffer 
+                // for the encoded representation.
+                var encodingBuffer = dataBuffer.Slice(dataBuffer.Length - dataByteLength);
+                var bytesWritten = encoding.GetBytes(dataAsSpan, encodingBuffer);
+            
+                var index = 0;
+                foreach (var symbol in encodingBuffer.Slice(0, bytesWritten))
                 {
-                    encoded.Append('%');
-
-                    // Break apart the byte into two four-bit components and
-                    // then convert each into their hexadecimal equivalent.
-                    byte b = (byte)symbol;
-                    int hiNibble = b >> 4;
-                    int loNibble = b & 0xF;
-                    encoded.Append(ToUpperHex(hiNibble));
-                    encoded.Append(ToUpperHex(loNibble));
+                    if (unreservedChars.IndexOf((char)symbol) != -1)
+                    {
+                        dataBuffer[index++] = symbol;
+                    }
+                    else
+                    {
+                        dataBuffer[index++] = (byte)'%';
+
+                        // Break apart the byte into two four-bit components and
+                        // then convert each into their hexadecimal equivalent.
+                        var hiNibble = symbol >> 4;
+                        var loNibble = symbol & 0xF;
+                        dataBuffer[index++] = (byte)ToUpperHex(hiNibble);
+                        dataBuffer[index++] = (byte)ToUpperHex(loNibble);
+                    }
                 }
+
+                return encoding.GetString(dataBuffer.Slice(0, index));
+            }
+            finally
+            {
+                if (sharedDataBuffer != null) ArrayPool<byte>.Shared.Return(sharedDataBuffer);
+            }
+        }
+        
+        internal static bool TryGetRFCEncodingSchemes(int rfcNumber, out string encodingScheme)
+        {
+            if (rfcNumber == 3986)
+            {
+                encodingScheme = ValidUrlCharacters;
+                return true;
             }
 
-            return encoded.ToString();
+            if (rfcNumber == 1738)
+            {
+                encodingScheme = ValidUrlCharactersRFC1738;
+                return true;
+            }
+
+            encodingScheme = null;
+            return false;
         }
 
         private static void ToHexString(Span<byte> source, Span<char> destination, bool lowercase)
diff --git a/sdk/src/Core/Amazon.Util/_bcl+netstandard/Extensions.cs b/sdk/src/Core/Amazon.Util/_bcl+netstandard/Extensions.cs
new file mode 100644
index 000000000000..bc496f8ed99b
--- /dev/null
+++ b/sdk/src/Core/Amazon.Util/_bcl+netstandard/Extensions.cs
@@ -0,0 +1,70 @@
+using System;
+using System.Globalization;
+using System.Text;
+
+namespace Amazon.Util
+{
+    internal static class Extensions
+    {
+        internal static string ToUpper(this String str, CultureInfo culture)
+        {
+            if (culture != CultureInfo.InvariantCulture)
+                throw new ArgumentException("The extension method ToUpper only works for invariant culture");
+            return str.ToUpperInvariant();
+        }
+
+#if NETSTANDARD || NETFRAMEWORK
+        /// <summary>
+        ///     Encodes into a span of bytes a set of characters from the specified read-only span.
+        /// </summary>
+        /// <param name="encoding">The encoding to be used.</param>
+        /// <param name="src">The span containing the set of characters to encode.</param>
+        /// <param name="dest">The byte span to hold the encoded bytes.</param>
+        /// <returns>The count of encoded bytes.</returns>
+        /// <remarks>
+        ///     The method was introduced as a compatibility shim for .NET Standard and can be replaced for target frameworks that provide those methods out of the box.
+        /// </remarks>
+        /// <seealso
+        ///     href="https://docs.microsoft.com/dotnet/api/system.text.encoding.getbytes?view=netstandard-2.1#system-text-encoding-getbytes(system-readonlyspan((system-char))-system-span((system-byte)))" />
+        public static unsafe int GetBytes(this Encoding encoding,
+            ReadOnlySpan<char> src,
+            Span<byte> dest)
+        {
+            if (src.Length == 0) return 0;
+
+            if (dest.Length == 0) return 0;
+
+            fixed (char* charPointer = src)
+            {
+                fixed (byte* bytePointer = dest)
+                {
+                    return encoding.GetBytes(
+                        charPointer,
+                        src.Length,
+                        bytePointer,
+                        dest.Length);
+                }
+            }
+        }
+
+        /// <summary>
+        ///     When overridden in a derived class, decodes all the bytes in the specified byte span into a string.
+        /// </summary>
+        /// <param name="encoding">The encoding to be used.</param>
+        /// <param name="bytes">A read-only byte span to decode to a Unicode string.</param>
+        /// <returns>A string that contains the decoded bytes from the provided read-only span.</returns>
+        /// <remarks>
+        ///     The method was introduced as a compatibility shim for .NET Standard and can be replaced for target frameworks that provide those methods out of the box.
+        /// </remarks>
+        public static unsafe string GetString(this Encoding encoding, ReadOnlySpan<byte> bytes)
+        {
+            if (bytes.Length == 0) return string.Empty;
+
+            fixed (byte* bytePointer = bytes)
+            {
+                return encoding.GetString(bytePointer, bytes.Length);
+            }
+        }
+#endif
+    }
+}
diff --git a/sdk/src/Core/Amazon.Util/_netstandard/Extensions.cs b/sdk/src/Core/Amazon.Util/_netstandard/Extensions.cs
deleted file mode 100644
index 792f332675e1..000000000000
--- a/sdk/src/Core/Amazon.Util/_netstandard/Extensions.cs
+++ /dev/null
@@ -1,18 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Globalization;
-using System.Linq;
-using System.Threading.Tasks;
-
-namespace Amazon.Util
-{
-    internal static class Extensions
-    {
-        internal static string ToUpper(this String str, CultureInfo culture)
-        {
-            if (culture != CultureInfo.InvariantCulture)
-                throw new ArgumentException("The extension method ToUpper only works for invariant culture");
-            return str.ToUpperInvariant();
-        }
-    }
-}
diff --git a/sdk/test/NetStandard/UnitTests/Core/AWSSDKUtilsTests.cs b/sdk/test/NetStandard/UnitTests/Core/AWSSDKUtilsTests.cs
index 159d35e9bb5b..943692170f4b 100644
--- a/sdk/test/NetStandard/UnitTests/Core/AWSSDKUtilsTests.cs
+++ b/sdk/test/NetStandard/UnitTests/Core/AWSSDKUtilsTests.cs
@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using Amazon.Util;
 using System.Text;
 using Amazon.Runtime.Internal;
@@ -63,5 +63,26 @@ public void DetermineService(string url, string expectedService)
 
             Assert.Equal(expectedService, service);
         }
+
+        [Theory]
+        [InlineData("value, with special chars!", "value%2C%20with%20special%20chars%21")]
+        [InlineData("value, with special chars and path {/+:}", "value%2C%20with%20special%20chars%20and%20path%20%7B%2F%2B%3A%7D")]
+        public void UrlEncodeWithoutPath(string input, string expected)
+        {
+            var encoded = AWSSDKUtils.UrlEncode(input, path: false);
+
+            Assert.Equal(expected, encoded);
+        }
+
+        [Theory]
+        [InlineData("\ud83d\ude02 value, with special chars!", "%F0%9F%98%82%20value%2C%20with%20special%20chars!")]
+        [InlineData("value, with special chars!", "value%2C%20with%20special%20chars!")]
+        [InlineData("value, with special chars and path {/+:}", "value%2C%20with%20special%20chars%20and%20path%20%7B/%2B:%7D")]
+        public void UrlEncodeWithPath(string input, string expected)
+        {
+            var encoded = AWSSDKUtils.UrlEncode(input, path: true);
+
+            Assert.Equal(expected, encoded);
+        }
     }
 }