How can I improve performance of Field.set (perhap using MethodHandles)?

I'm writing some code that calls Field.set and Field.get many many thousands of times. Obviously this is very slow because of the reflection.

I want to see if I can improve performance using MethodHandle in Java 7. So far here's what I have:

Instead of field.set(pojo, value), I'm doing:

private static final Map<Field, MethodHandle> setHandles = new HashMap<>();MethodHandle mh = setHandles.get(field);if (mh == null) {    mh = lookup.unreflectSetter(field);    setHandles.put(field, mh);}mh.invoke(pojo, value);

However, this doesn't seem to perform better than the Field.set call using reflection. Am I doing something wrong here?

I read that using invokeExact could be faster but when I tried using that I got a java.lang.invoke.WrongMethodTypeException.

Has anyone successfully been able to optimize repeated calls to Field.set or Field.get?