decent performance from G4 Macs?

[Mark Hahn]

I'm doing some benchmarks to evaluate whether current Macs
would make suitable nodes for a serial farm (lots of nodes,
preferably fast CPU and dram, but no serious interconnect.)
I've tried a variety of real codes and benchmarks, but can't
seem to get something like a Mac G4/800 with PC133 to perform
anywhere close to even a P4/1.7/i845/PC133.

I'm using either the gcc 2.95 that comes with OSX or a 
recent 3.1 snapshot (which is MUCH better, but still bad).

is it just that the performance Apple brags about is strictly
in-cache, and/or when doing something ah specialized like 
single-precision SIMD (altivec/velocity engine)?

I haven't really pushed to track down an account on the very
latest dual G4/1000, but afaikt it's got the same boring PC133.

is anyone using Macs in clusters, and what kind of performance
are you observing?

thanks, mark hahn.