The game engine (Unreal1 - UT99) was not designed for processors that dynamically change their clock speed during runtime. As a result you might experience strange gameplay speed when running the game on such processors. This is not a Wine specific bug.
The best workaround is to disable dynamic clock speed and/or processor power management.
NOTE: Simply changing the gamespeed with the "slomo" cheat is not a good solution as it will only mess up your game even more. Also, "slomo" does not work in multiplayer.