diff --git a/sdk/src/Core/Amazon.Util/AWSSDKUtils.cs b/sdk/src/Core/Amazon.Util/AWSSDKUtils.cs
index 7c2a13fecdc5..e25e74bc7fc6 100644
--- a/sdk/src/Core/Amazon.Util/AWSSDKUtils.cs
+++ b/sdk/src/Core/Amazon.Util/AWSSDKUtils.cs
@@ -195,8 +195,31 @@ private static string DetermineValidPathCharacters()
         /// <returns></returns>
         public static string GetExtension(string path)
         {
-            if (path == null)
+            if (path is null)
                 return null;
+
+#if NET8_0_OR_GREATER
+            // LastIndexOf and LastIndexOfAny is vectorized on .NET8+ and is
+            // significantly faster for cases where 'path' does not end with a short file
+            // extension, such as GUIDs
+            ReadOnlySpan<char> pathSpan = path.AsSpan();
+            int extensionIndex = pathSpan.LastIndexOf('.');
+            if (extensionIndex == -1)
+            {
+                return string.Empty;
+            }
+
+            int directoryIndex = pathSpan.LastIndexOfAny('/', '\\', ':');
+
+            // extension separator is found and exists before path separator or path separator doesn't exist
+            // AND it's not the last one in the string
+            if (directoryIndex < extensionIndex && extensionIndex < pathSpan.Length - 1)
+            {
+                return pathSpan.Slice(extensionIndex).ToString();
+            }
+
+            return string.Empty;
+#else
             int length = path.Length;
             int index = length;
 
@@ -213,15 +236,16 @@ public static string GetExtension(string path)
                 else if (IsPathSeparator(ch))
                     break;
             }
+
             return string.Empty;
-        }
 
-        // Checks if the character is one \ / :
-        private static bool IsPathSeparator(char ch)
-        {
-            return (ch == '\\' ||
-                    ch == '/' ||
-                    ch == ':');
+            bool IsPathSeparator(char ch)
+            {
+                return (ch == '\\' ||
+                        ch == '/' ||
+                        ch == ':');
+            }
+#endif
         }
 
         /*
diff --git a/sdk/test/NetStandard/UnitTests/Core/AWSSDKUtilsTests.cs b/sdk/test/NetStandard/UnitTests/Core/AWSSDKUtilsTests.cs
index 943692170f4b..8723e0b53785 100644
--- a/sdk/test/NetStandard/UnitTests/Core/AWSSDKUtilsTests.cs
+++ b/sdk/test/NetStandard/UnitTests/Core/AWSSDKUtilsTests.cs
@@ -84,5 +84,22 @@ public void UrlEncodeWithPath(string input, string expected)
 
             Assert.Equal(expected, encoded);
         }
+
+        [Theory]
+        [InlineData(null, null)]
+        [InlineData("no-delimiters-at-all", "")]
+        [InlineData("delimiter-end-of-string.", "")]
+        [InlineData("relative-path/no-file-extension", "")]
+        [InlineData("relative-path\\no-file-extension", "")]
+        [InlineData("relative-path:no-file-extension", "")]
+        [InlineData("simple-file.pdf", ".pdf")]
+        [InlineData("relative-path/with-file-extension.pdf", ".pdf")]
+        [InlineData("relative-path.with-dot/with-file-extension.pdf", ".pdf")]
+        public void GetExtension(string input, string expected)
+        {
+            var actual = AWSSDKUtils.GetExtension(input);
+
+            Assert.Equal(expected, actual);
+        }
     }
 }
diff --git a/sdk/test/UnitTests/Custom/Util/AWSSDKUtilsTests.cs b/sdk/test/UnitTests/Custom/Util/AWSSDKUtilsTests.cs
index d81f11cc2b45..3cd8c6982c21 100644
--- a/sdk/test/UnitTests/Custom/Util/AWSSDKUtilsTests.cs
+++ b/sdk/test/UnitTests/Custom/Util/AWSSDKUtilsTests.cs
@@ -12,13 +12,11 @@
  * express or implied. See the License for the specific language governing
  * permissions and limitations under the License.
  */
+using Amazon.Util;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using System;
 using System.IO;
-using Amazon.Util;
 using System.Reflection;
-using Moq;
-using Amazon.Util.Internal;
 using System.Text;
 
 namespace AWSSDK.UnitTests
@@ -178,5 +176,24 @@ public void ToHex(string input, bool lowercase, string expectedResult)
 
             Assert.AreEqual(expectedResult, hexString);
         }
+
+        [TestCategory("UnitTest")]
+        [TestCategory("Util")]
+        [DataTestMethod]
+        [DataRow(null, null)]
+        [DataRow("no-delimiters-at-all", "")]
+        [DataRow("delimiter-end-of-string.", "")]
+        [DataRow("relative-path/no-file-extension", "")]
+        [DataRow("relative-path\\no-file-extension", "")]
+        [DataRow("relative-path:no-file-extension", "")]
+        [DataRow("simple-file.pdf", ".pdf")]
+        [DataRow("relative-path/with-file-extension.pdf", ".pdf")]
+        [DataRow("relative-path.with-dot/with-file-extension.pdf", ".pdf")]
+        public void GetExtension(string input, string expected)
+        {
+            var actual = AWSSDKUtils.GetExtension(input);
+
+            Assert.AreEqual(expected, actual);
+        }
     }
 }