Finally found some decently priced and WORKING CL2 rated 256mb modules of PC133 for my P3 so I did some quick benchmarking to compare CL3 timings to CL2. This is with an overclocked TI4200 graphics card. Previously I had a 5900XT in here but after a power outage in my neighbourhood the 5900XT is throwing up an insufficent power message. This happens regardless of what motherboard and power supply I have it connected to.

Specs:
Asus CUBX-E
Pentium 3 1.4-S
512MB PC133 (2x256 Infineon modules)
Asus TI4200 (overclocked to 320 core / 570 mem)

Anyway onto the results:
512MB PC133 CL3 (3-3-3-10 timings)
3dmark 99 - 10488
3dmark 2000 - 9901
3dmark 2001 - 8391
3dmark 2003 - 1476
Aquamark - 18228
Quake 3 - 116.5fps
Sandra 2001 Memory Benchmark:
Int ALU/RAM Bandwidth - 317 MB /s
Float FPU/RAM Bandwidht - 318 MB /s

512MB PC133 CL2 (2-2-2-8 timings)
3dmark 99 - 11086
3dmark 2000 - 10481
3dmark 2001 - 8955
3dmark 2003 - 1518
Aquamark - 18509
Quake 3 - 126.8fps
Sandra 2001 Memory Benchmark:
Int ALU/RAM Bandwidth - 406 MB /s
Float FPU/RAM Bandwidht - 409 MB /s

EDIT - I've run the sandra memory benchmark several times on the slower memory now and it varies up and down a bit but those 317/318 numbers are fairly consistent. I was not expecting such a big difference in that result.