名前忘れたがその辺で売ってる安物だよ
WinXP, Celeron 2.66GHz, 480 MB RAM

clisp の出力ぐらいなら貼り付けとこうか

[9]> (time (log (gcd (expt 2 (ceiling (* 960 (log 3 2)))) (1- (expt 3 960))) 2))

Real time: 0.0 sec.
Run time: 0.0 sec.
Space: 2800 Bytes
8
[10]> (time (log (gcd (expt 2 (ceiling (* 9600 (log 3 2)))) (1- (expt 3 9600))) 2))

Real time: 0.015625 sec.
Run time: 0.015625 sec.
Space: 14400 Bytes
9