Performance tweak when creating md5 digest about spymemcached HOT 2 CLOSED

This measures slower on my machine:

5 threads, 10 in pool, mode: NEW
Processing time:  71ms
15 threads, 10 in pool, mode: NEW
Processing time:  229ms
50 threads, 10 in pool, mode: NEW
Processing time:  776ms
5 threads, 10 in pool, mode: LOCKED
Processing time:  102ms
15 threads, 10 in pool, mode: LOCKED
Processing time:  331ms
50 threads, 10 in pool, mode: LOCKED
Processing time:  1166ms

Run the attached test to try it against yours.

BTW, if performance is a concern, you should really use a different hash.  md5 
was
designed to be of cryptographic quality, not for performance.