Thinking it might be a disk I/O problem, I tried a multithreaded compile (make "MAKE=make -j 3" -j 3 bzImage) to see if it would keep the CPU fed better. One hour and forty-seven minutes later, a single kernel compile finished. The same compile on an 800MHz Athlon takes under three minutes, so naturally, I am thinking there are serious problems with the Abit VA6 and/or the VIA Apollo Pro 133 chipset in Linux (or at least in Red Hat 6.0). I've not heard of any problems, but I really don't know what kind of support Linux includes for non-Intel chipsets, so I dunno.
I'm baffled. Any ideas?