I have a problem with TR 2 and 3 - the more I play both games, the less frames per second I get, and after some 10 mins of playing, it all becomes very annoying and the movement is not fluid at all. My PC dates back from 2006, but it should be fine to run these games (GeForce 6600 GT, Intel Celeron 2.81 GHz, 2.50 GB of RAM).

Any ideas? Thank you in advance.