Can access by local method variables be faster then access by member variables ?

[Martin Buchholz]

The practice in java.util.concurrent, following Doug Lea,
is to copy an unmodified field into a local
at the beginning of a method,
and then use that local for the duration of the method
E.g.:

    private void interruptWorkers() {
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
........................
          } finally {
            mainLock.unlock();
        }
    }

It is believed this gives a performance win
even when the field in question is final,
where the jit (or even javac?) should be
able to easily make such an optimization.

Martin