--- old/src/share/classes/java/lang/StringBuffer.java	2013-05-10 01:10:13.398680589 -0400
+++ new/src/share/classes/java/lang/StringBuffer.java	2013-05-10 01:10:12.126609573 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1994, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -98,6 +98,12 @@
     implements java.io.Serializable, CharSequence
 {
 
+    /**
+     * A cache of the last value returned by toString. Cleared
+     * whenever the StringBuffer is modified.
+     */
+    private transient String toStringCache;
+
     /** use serialVersionUID from JDK 1.0.2 for interoperability */
     static final long serialVersionUID = 3388685877147921107L;
 
@@ -184,6 +190,7 @@
     @Override
     public synchronized void setLength(int newLength) {
         super.setLength(newLength);
+        toStringCache = null;
     }
 
     /**
@@ -248,17 +255,20 @@
         if ((index < 0) || (index >= count))
             throw new StringIndexOutOfBoundsException(index);
         value[index] = ch;
+        toStringCache = null;
     }
 
     @Override
     public synchronized StringBuffer append(Object obj) {
         super.append(String.valueOf(obj));
+        toStringCache = null;
         return this;
     }
 
     @Override
     public synchronized StringBuffer append(String str) {
         super.append(str);
+        toStringCache = null;
         return this;
     }
 
@@ -288,6 +298,7 @@
      */
     public synchronized StringBuffer append(StringBuffer sb) {
         super.append(sb);
+        toStringCache = null;
         return this;
     }
 
@@ -297,6 +308,7 @@
     @Override
     synchronized StringBuffer append(AbstractStringBuilder asb) {
         super.append(asb);
+        toStringCache = null;
         return this;
     }
 
@@ -325,6 +337,7 @@
     public StringBuffer append(CharSequence s) {
         // Note, synchronization achieved via invocations of other StringBuffer methods after
         // narrowing of s to specific type
+        // Ditto for toStringCache clearing
         super.append(s);
         return this;
     }
@@ -337,12 +350,14 @@
     public synchronized StringBuffer append(CharSequence s, int start, int end)
     {
         super.append(s, start, end);
+        toStringCache = null;
         return this;
     }
 
     @Override
     public synchronized StringBuffer append(char[] str) {
         super.append(str);
+        toStringCache = null;
         return this;
     }
 
@@ -352,24 +367,28 @@
     @Override
     public synchronized StringBuffer append(char[] str, int offset, int len) {
         super.append(str, offset, len);
+        toStringCache = null;
         return this;
     }
 
     @Override
     public synchronized StringBuffer append(boolean b) {
         super.append(b);
+        toStringCache = null;
         return this;
     }
 
     @Override
     public synchronized StringBuffer append(char c) {
         super.append(c);
+        toStringCache = null;
         return this;
     }
 
     @Override
     public synchronized StringBuffer append(int i) {
         super.append(i);
+        toStringCache = null;
         return this;
     }
 
@@ -379,24 +398,28 @@
     @Override
     public synchronized StringBuffer appendCodePoint(int codePoint) {
         super.appendCodePoint(codePoint);
+        toStringCache = null;
         return this;
     }
 
     @Override
     public synchronized StringBuffer append(long lng) {
         super.append(lng);
+        toStringCache = null;
         return this;
     }
 
     @Override
     public synchronized StringBuffer append(float f) {
         super.append(f);
+        toStringCache = null;
         return this;
     }
 
     @Override
     public synchronized StringBuffer append(double d) {
         super.append(d);
+        toStringCache = null;
         return this;
     }
 
@@ -407,6 +430,7 @@
     @Override
     public synchronized StringBuffer delete(int start, int end) {
         super.delete(start, end);
+        toStringCache = null;
         return this;
     }
 
@@ -417,6 +441,7 @@
     @Override
     public synchronized StringBuffer deleteCharAt(int index) {
         super.deleteCharAt(index);
+        toStringCache = null;
         return this;
     }
 
@@ -427,6 +452,7 @@
     @Override
     public synchronized StringBuffer replace(int start, int end, String str) {
         super.replace(start, end, str);
+        toStringCache = null;
         return this;
     }
 
@@ -466,6 +492,7 @@
                                             int len)
     {
         super.insert(index, str, offset, len);
+        toStringCache = null;
         return this;
     }
 
@@ -475,6 +502,7 @@
     @Override
     public synchronized StringBuffer insert(int offset, Object obj) {
         super.insert(offset, String.valueOf(obj));
+        toStringCache = null;
         return this;
     }
 
@@ -484,6 +512,7 @@
     @Override
     public synchronized StringBuffer insert(int offset, String str) {
         super.insert(offset, str);
+        toStringCache = null;
         return this;
     }
 
@@ -493,6 +522,7 @@
     @Override
     public synchronized StringBuffer insert(int offset, char[] str) {
         super.insert(offset, str);
+        toStringCache = null;
         return this;
     }
 
@@ -504,6 +534,7 @@
     public StringBuffer insert(int dstOffset, CharSequence s) {
         // Note, synchronization achieved via invocations of other StringBuffer methods
         // after narrowing of s to specific type
+        // Ditto for toStringCache clearing
         super.insert(dstOffset, s);
         return this;
     }
@@ -517,6 +548,7 @@
             int start, int end)
     {
         super.insert(dstOffset, s, start, end);
+        toStringCache = null;
         return this;
     }
 
@@ -527,6 +559,7 @@
     public  StringBuffer insert(int offset, boolean b) {
         // Note, synchronization achieved via invocation of StringBuffer insert(int, String)
         // after conversion of b to String by super class method
+        // Ditto for toStringCache clearing
         super.insert(offset, b);
         return this;
     }
@@ -537,6 +570,7 @@
     @Override
     public synchronized StringBuffer insert(int offset, char c) {
         super.insert(offset, c);
+        toStringCache = null;
         return this;
     }
 
@@ -547,6 +581,7 @@
     public StringBuffer insert(int offset, int i) {
         // Note, synchronization achieved via invocation of StringBuffer insert(int, String)
         // after conversion of i to String by super class method
+        // Ditto for toStringCache clearing
         super.insert(offset, i);
         return this;
     }
@@ -558,6 +593,7 @@
     public StringBuffer insert(int offset, long l) {
         // Note, synchronization achieved via invocation of StringBuffer insert(int, String)
         // after conversion of l to String by super class method
+        // Ditto for toStringCache clearing
         super.insert(offset, l);
         return this;
     }
@@ -569,6 +605,7 @@
     public StringBuffer insert(int offset, float f) {
         // Note, synchronization achieved via invocation of StringBuffer insert(int, String)
         // after conversion of f to String by super class method
+        // Ditto for toStringCache clearing
         super.insert(offset, f);
         return this;
     }
@@ -580,6 +617,7 @@
     public StringBuffer insert(int offset, double d) {
         // Note, synchronization achieved via invocation of StringBuffer insert(int, String)
         // after conversion of d to String by super class method
+        // Ditto for toStringCache clearing
         super.insert(offset, d);
         return this;
     }
@@ -624,12 +662,18 @@
     @Override
     public synchronized StringBuffer reverse() {
         super.reverse();
+        toStringCache = null;
         return this;
     }
 
     @Override
     public synchronized String toString() {
-        return new String(value, 0, count);
+        if (toStringCache == null) {
+            toStringCache = new String(value, 0, count);
+            return toStringCache;
+        } else {
+            return new String(toStringCache);
+        }
     }
 
     /**