I have been benchmarking Pentium 4 boxes against my Pentium III laptop with the exact same kernel and executables as well as custom compiled kernels. The Pentium III has a much lower clock rate and I have noticed that system call performance (and hence io performance) is up to an order of magnitude higher on my Pentium III laptop. 1k block IO reads/writes are anemic on the Pentium 4, for example,