'Ello,
I recently sprung for Windows 7 and installed it on my desktop. Everything is running well, but I have some pretty nasty performance issues in most Source games (particularly TF2), but the problems are also moderately present in other engines (Borderlands/Mirror's Edge, etc.). The issue is that periodically, roughly every 3 to 4 seconds, my framerate will drop to a noticable 10-20 FPS for a split second, then return to normal.
During the "normal" moments of gameplay, my framerate hovers along a nice 60 FPS (unless I'm in some major combat). I have tried lowering my resolution to 640 x 480, making sure background programs and services are off (Like Opera, and I've screwed with msconfig a few times), running CCleaner, disabling my second monitor so that Windows isn't being drawn while TF2 is running, and disabling multicore rendering. None of these attempts have done anything to help.
I've noticed that the problem becomes increasingly present from the time I've launched the game to several minutes into gameplay. The issue also seems more present in network gameplay than single-player games (but then again, Episode Two has always out-performed TF2 for some reason). +Showbudget, as you can see below, is reporting a bunch of resource-hogs, but the culprits tend to be somewhat random in their appearance. The only recurring performance-killers, according to +showbudget, are Game and Mat_threadedendframe, whatever that last one has to do with.
Any help is much appreciated! I haven't been able to find much useful information online, so I'm thinking of going to Steam Support with this one if I can't get it resolved soon.