diff --git a/CHANGELOG b/CHANGELOG
index f5df87f..8934083 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,7 @@
+* String#startsWith, String#endsWith performance optimization (Yaffle, Tobie Langel, kangax)
+
+* Rewrite String#camelize using String#replace with a replacement function (Phred, John-David Dalton, Samuel Lebeau, kangax)
+
 *1.6.1* (August 24, 2009)
 
 * Avoid triggering a warning when Java is disabled in IE8. [#668 state:resolved] (orv, kangax, Andrew Dupont, Tobie Langel)
diff --git a/src/lang/string.js b/src/lang/string.js
index 16935a7..3c7f23f 100644
--- a/src/lang/string.js
+++ b/src/lang/string.js
@@ -429,7 +429,7 @@ Object.extend(String.prototype, (function() {
    *  Checks if the string starts with `substring`.
   **/
   function startsWith(pattern) {
-    return this.indexOf(pattern) === 0;
+    return !this.lastIndexOf(pattern,0);
   }
 
   /**
@@ -439,7 +439,7 @@ Object.extend(String.prototype, (function() {
   **/
   function endsWith(pattern) {
     var d = this.length - pattern.length;
-    return d >= 0 && this.lastIndexOf(pattern) === d;
+    return d >= 0 && this.indexOf(pattern,d) === d;
   }
 
   /**