Source : Webster's Revised Unabridged Dictionary (1913)

Presto \Pres"to\, adv. [It. or Sp. presto quick, quickly. See
   {Prest}, a.]
   1. Quickly; immediately; in haste; suddenly.

            Presto! begone! 'tis here again.      --Swift.

   2. (Mus.) Quickly; rapidly; -- a direction for a quick,
      lively movement or performance; quicker than allegro, or
      any rate of time except prestissimo.

Source : WordNet®

presto
     adj : (of tempo) very fast
     adv 1: suddenly; "Presto! begone! 'tis here again"- Swift
     2: at a very fast tempo (faster than allegro)

Source : Free On-Line Dictionary of Computing

PRESTO
     
        A parallel language for shared-memory multiprocessors, built
        on top of C++ by Bershad et al, U Washington 1987.  PRESTO
        provides {class}es for {thread}s and {spinlock}s as well as
        {Mesa}-style {monitor}s and {condition variable}s.
     
        {(ftp://cs.washington.edu/pub/presto1.0.tar.Z)}.  E-mail:
        .
     
        ["PRESTO: A Kernel for Parallel Programming Environments",
        B.N. Bershad et al, U Wash CS TR, Jan 1987].