TF2 Performance issues despite good FPS
I'm running Ubuntu 13.04 with an AMD 6630M and the AMD 13.4 drivers. I run TF2 on Windows on the same machine, and despite getting 30-40 fps, the game is quite playable, very smooth and responsive.
I've noticed that on Linux, I get the same, even higher fps most of the time, but even when I turn down the graphics settings, the game isn't quite as responsive. There's a delay between when I move the mouse and when the game responds, which makes it incredibly difficult to steer my character.
I'm wondering, 1. how do I go about diagnosing the source of the performance issues, and
2. what settings do I tinker with to try to fix them?
I'm an experienced linux/command line user, but less familiar with steam program configurations. I'm definitely willing to get my hands dirty and experiment if it means I can get a playable TF2 on linux. I'd love to have one less reason to boot into Windows.