Do you have software mixing configured for sound? Looks like something is using sound resources and FS2_Open can't use them... Are you getting any sound from the game at all? And out of curiosity - why OSD instead of ALSA?
And do you have libopenal -package installed...? Dunno if you can even start the game without that one, though, so the question might be redundant...
As far as slowness goes - what kind of graphics card are you using? And if you're running any 3D desktop rendering like Beryl/Compiz, disable it while you're playing the game.
It's also possible that the sound issues are causing slowness (?); to check out this possibility, try runnign the game with -nosound command line option, and check if it's just as slow then.
Couldn't hurt to post actual spects of the PC either... CPU, memory, GPU most importantly.