Hi.. I have same problem.
First, I collected some computer specs from our small TC:E portuguese comunity that had same problem:
1)2.6.17-9-386, intel pentium 4 3.2ghz ceder mill, 1gb ram, nvidia geforce 7900gt, Intel Corporation 82801G (ICH7 Family) AC'97 Audio Controller
2)Linux main 2.6.16-gentoo-r9 #3 SMP PREEMPT Sun Jul 2 19:48:45 GMT 2006 i686 Intel(R) Pentium(R) 4 CPU 2.66GHz GenuineIntel GNU/Linux,512MB ram, 20GB partition in reiserfs, Nvidia GeForce 4 mx 440, gentoo i686
3)Intel celeron 2ghz, 768mb ram, msi motherboard something, audigy 2 zs, nv 6600gt
And my self:
4)os[Linux 2.6.18-ck1 i686] distro[Gentoo Linux "~x86"] cpu[2 x Intel(R) Pentium(R) 4 CPU 2.80GHz (GenuineIntel) @ 3.21GHz] mem[Physical : 2.0GB, 61.8% free] disk[Total : 213.94GB, 50.40% Free] video[nVidia Corporation NV31 [GeForce FX 5600]] sound[EMU10K1 - SBLive! Value [CT4832]]
Facts:
-In 0.48 i had game options with 44khz and no firelag at all
-hunkmegs=1024, sound megs=128 and zonemegs=256 didn't fix anything.
-In 0.49 with " seta s_khz "32" " firelag is completly gone.
-No low FPS during the game(it runs very very well).. It's not the graphic card.
-Makes the game unplayable