AMD64 timings

using ISO C
mult
  512-bit:       496
 1024-bit:      1717
 2048-bit:      7200
sqr
  512-bit:       448
 1024-bit:      1760
 2048-bit:      7099
mont
  512-bit:      1416
 1024-bit:      5156
 2048-bit:     20820
expt
  512-bit:   1520207
 1024-bit:  10603520
 2048-bit:  84893649

using amd64
mult
  512-bit:       292
 1024-bit:       945
 2048-bit:      3620
sqr
  512-bit:       238
 1024-bit:       801
 2048-bit:      2853
mont
  512-bit:       731
 1024-bit:      1730
 2048-bit:      5462
Exptmod:
  512-bit:    641743
 1024-bit:   3167406
 2048-bit:  20158609

LTM exptmods

Exponentiating   513-bit =>       825/sec,   2183028 cycles
Exponentiating  1025-bit =>       151/sec,  11900720 cycles
Exponentiating  2049-bit =>        24/sec,  72376416 cycles