I have: net_clientLagOMeter and com_showFPS cvars set to ON so I can see the network performance. If I just start a map or I am in a room, the lag o meter shows green and my FPS are ok. After the game plays a little, or I go right into action, the lagometer shows yellow and red and my FPS falls to around 5. Unplayable. I tried new drivers, old drivers, previous kernel, but got same results. I turned the quality settings down to low for graphics and it played the same.
The console has no performance messages.
I tried different servers, and against computer. It was actually playing against computer that I thought something was wrong since the performance dropped as more bots spawned. The gameplay and graphics felt like it did when I first started playing with a slower computer and a 6600GT: OK sometimes, but not playable.
For now, I loaded up the Hardy release (8.04) with the latest NVidia driver and it runs great again. I shrunk the partition with 9.04 and added the new partition for 8.04. I mounted the old partition and use the same binary and settings for ETQW so I know that it is not something I did to my ETQW installation or settings.
I doubt the kernel, but I suspect the new X server in Ubuntu 9.04.