For everything you will probably ever use your computer for the PC133 is going to be faster. I have seen some very specific applications used in business where latency is the only issue and bandwidth makes no difference and in those cases the PC100 CAS2 will be faster. So I would say that 99.9% of the time the PC133 is going to be faster. However, I helped build a machine specifically for the purpose of running that application and we ran various benchmarks to create the lowest latency set-up as possible because it made the difference of 6-10 hours in how long it would run.