--- a/langtools/src/share/classes/com/sun/tools/javac/comp/Lower.java	Wed Oct 10 18:34:46 2012 -0700
+++ b/langtools/src/share/classes/com/sun/tools/javac/comp/Lower.java	Wed Oct 10 18:44:21 2012 -0700
@@ -1945,7 +1945,7 @@
      *  @param sig      The signature of type T.
      */
     private Name cacheName(String sig) {
-        StringBuffer buf = new StringBuffer();
+        StringBuilder buf = new StringBuilder();
         if (sig.startsWith("[")) {
             buf = buf.append("array");
             while (sig.startsWith("[")) {