i run the game on a P4 3Ghz with a 9800XT 128MB and 1024 Mb RAM which is not really Hi-End nowadays ...
It runs lets say okay, a not-that-smooth 20 fps at max settings and 1024x768 is okay, but sometimes there is something really strange i encountered. it runs for a certain time with 5fps or less, just stops after lets say 2 min.
but the most strange thing, it happens in special areas, often with plenty of wood
and, wow, i just defragmentated my systen with Perfect Disk and it does not appear anymore. cool .