Ran this command on the same server, RaQ3 512MB, with each CPU.
System Multiplier and Core Voltage adjusted for the CPU.
  "time tar -czpsvf usr.tgz /usr"
Please note the "nn:nn:nn elapsed"

K6-2/300AFR (64KB Cache) (runing at 300MHz)
  1133.71 user 51.96 system 22:02.09 elapsed
  89%CPU (0avgtext+0avgdata   0maxresident)k
  0inputs+0outputs (146544major+324minor) pagefaults 0swaps

K6-2/475ACK (64KB Cache) (running at 450MHz)
  1015.86 user 50.40 system 19:57.45 elapsed
  89%CPU (0avgtext+0avgdata 0maxresident)k
  0inputs+0outputs (146782 major+324 minor) pagefaults 0swaps

K6-2/500AFX (64KB Cache) (running at 500MHz)
  1005.90 user 50.18 system 19:10.84 elapsed
  91%CPU (0avgtext+0avgdata 0maxresident)k
  0inputs+0outputs (146988 major+324 minor) pagefaults 0swaps

K6-2+/450ACR (128KB Cache) (running at 450MHz)
  416.15 user 47.78 system 9:52.62 elapsed
  78%CPU (0avgtext+0avgdata 0maxresident)k
  0inputs+0outputs (146542 major+324 minor)pagefaults 0swaps

K6-2+/550ACZ (128KB Cache) (running at 550 MHz)
  364.02 user 46.30 system 8:55.61 elapsed
  76%CPU (0avgtext+0avgdata 0maxresident)k
  0inputs+0outputs (146804 major+324 minor) pagefaults 0swaps

K6-III+/450ACZ (256KB Cache) (running at 450MHz)
  356.47 user 33.88 system 8:35.54 elapsed
  75%CPU (0avgtext+0avgdata 0maxresident)k
  0inputs+0outputs (146805 major+324 minor)pagefaults 0swaps

##################################################
# And the winner is K6-III+/450ACZ (256KB Cache) #
##################################################