I have been playing TF2 for a month or so now and I have had no problems holding 60fps. I have vsync enabled because without I get 100+ fps and really bad tearing.
Through the last few days I've noticed my frame rates will drop from 60 to less than 30 sometimes. Even if I'm in a tunnel with one other enemy it will freak out. It seems to be getting worse and doing it more often.
Anyone have any idea what could be causing this? I have not installed any new programs or anything. My temps when the frame rate drops occur are ~50C and ~58C for the CPU and GPU respectively so it is not an overheating issue.
AMD Athlon 64 X2 5000
Radeon HD4830 (OC'd to 675/1175)
4GB DDR2-800 (2x2GB)
PC P&C 500W PSU
TF2 is just really poorly optimized. I have an Athlon x2 4000+ (2.1GHz) and an HD4850, i'm hovering between 20 and 40 during any action, 60+ in places with few people. My friend with a Q6600 @ 3.4 and an HD4870 is hitting the same FPS as me.