Sound lag

All in-game sound lag by about a second for me. When I fire a gun, I will hear the gunshot roughly a second later. This annoys the piss out of me and I have no idea what’s causing it. The computer I’m on can handle the graphics just fine on low-medium settings, but the sound still lags on any setting.
Mid-2010 13" Macbook
Intel Core 2 Duo 2,4 GHz
Nvidia Geforce 320M 256mb
Built-in soundcard
8 gigs of DDR3 RAM
Mac OSX 10.7.4

Thankfully, I’m only stuck on this computer for another 4 days, but still, I need to fix this in case I want to bring it with me on vacation again.

Wait, how the fuck do you have DDR3 RAM if you have an Intel Core 2 Duo?

OT: I googled HL2 Sound lag, try putting in snd_mixahead 0.1 in console.

It’s 1067 MHz.
I’ll try that console command, brb.

[editline]22nd July 2013[/editline]

snd_mixahead 0.1 fixed it, problem solved.