System specs:

AN430TX (Intel 430TX) motherboard
Intel Pentium 233 MMX
ATI Rage XL 8MB
Windows 98
GL Quake v0.98 / 640x480x16

The 430TX is only capable of caching up to 64MB of memory, which causes a penalty to performance in operating systems like Windows 98 that map memory from the bottom-up (starting from the uncachable area). I wanted to see how obvious this might be in testing.

Two tests were performed for each configuration; one with a stock Rage XL PCI at 83.8/62.8 Mhz and another with it overclocked to 110.9/83.1 Mhz. Clock speed was set with PowerStrip and confirmed by HWiNFO.

128MB
20.7
22.6 @ overclock

64MB
23.7
26.3 @ overclock

Using less memory that is fully cachable and a slight overclock can bring mediocre performance to > 25 fps, which is much more enjoyable.

A similar specced system with a Rage XL AGP would perform even better, since these cards can provide a wider bus and a faster base clock speed.