--- a/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/Debug.java	Thu Oct 02 08:43:58 2014 -0700
+++ b/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/Debug.java	Thu Oct 02 10:54:54 2014 -0700
@@ -1210,9 +1210,13 @@
         return createTimer(format, arg1, arg2);
     }
 
-    public static Object convertFormatArg(Object arg) {
-        if (arg instanceof Class) {
-            Class<?> c = (Class<?>) arg;
+    /**
+     * There are paths where construction of formatted class names are common and the code below is
+     * surprisingly expensive, so compute it once and cache it.
+     */
+    private static final ClassValue<String> formattedClassName = new ClassValue<String>() {
+        @Override
+        protected String computeValue(Class<?> c) {
             final String simpleName = c.getSimpleName();
             Class<?> enclosingClass = c.getEnclosingClass();
             if (enclosingClass != null) {
@@ -1226,6 +1230,12 @@
                 return simpleName;
             }
         }
+    };
+
+    public static Object convertFormatArg(Object arg) {
+        if (arg instanceof Class) {
+            return formattedClassName.get((Class<?>) arg);
+        }
         return arg;
     }