I ran into this problem in both WindowsME and XP. While in multiplayer mode in Return to Castle Wolfenstein, I would get excessive page file activity which would get progressively worse. Map load times would constantly increase as each new map was loaded until the system reported WOLF.exe had caused and error and would shutdown the game.
The solution for my system is to set both the Desktop AND game color to 16-bit. Also, set both to the same resolution. I like 1280 x 1024, but that may be too high for some systems.
After this tweak, my map load times went from >1 min to between 10 and 20 seconds. Right where a P4 1.5 with 256 megs should be.