If I understand correctly, Baillie-PSW has been shown to be correct for all integers < 2^64, so for 64-bit ints you might use (some variant of) that instead of M-R.

Edited to add: Sieving has got to be much faster than M-R if you want all primes of a certain size. You would use M-R or Baillie-PSW if you are testing them one at a time.