For me, the game often refuses to acknowledge any input for several seconds, then suddenly notices that I have pressed/released buttons and updates, but promptly stops noticing again. For example, if I hold down the right arrow button (or tab, or w), it will wait a varying amount of time before noticing and before my ship starts turning. Then, when I release the button, it again takes a while. However, unlike normal lag, if I tap the button, it may start turning soon after, but not stop for several seconds. It is almost as if lots of packets are being dropped. Also, fps remains high (~400) and I still see bots moving and people chatting at normal rates, implying that it is a network problem. I suppose it is possible that my ISP (verizon dsl) is dropping a lot of outbound packets, so it may not be vendetta's fault. I just wonder if anyone else sees this too.

This occurs intermittently, but frequently enough to make combat with anything at all challenging impossible.
I'm running FC4 with a custom kernel based off kernel-2.6.16-1.2069_FC4 and vendetta in a separate X session. Hardware: AMD 64 3700+ (running in i386 however), nvidia 6600gt, 2gb ram.

And now its stopped happenning. Weird.

This isn't a network problem; the game does enough client-side prediction where you would always see input respond normally.

Since you're getting 400 fps, your video card is probably rendering way ahead of time and then "playing back" the frames. But that's pretty unusual in OpenGL, and I don't remember whether we have any sort of vsync option under linux. But if we do, it might help.

yeah ..with nvidia cards:

export __GL_SYNC_TO_VBLANK=1

with ati's drivers:

aticonfig --vs on
(although that doesn'T seem to work here)