I have this problem EVERY time I play Fallout: New Vegas. I've tried optimization crap, lowering graphics, everything! I can't get rid of this stupid audio lag/stutter that pops up every time the game loads stuff farther in the distance eg: walking from Goodsprings to Primm, the mountain rocks start to load, AUDIO LAG AND STUTTERING. I try to ignore it, but it's just impossible. I play on Medium settings with slightly boosted view distance.

Specs:
AMD Athlon 64 Processor 3800+ 2.40GHz
3.50 GB RAM
Nvidea GeForce 8600 GSO

You could try updating your audio drivers also if you have ffdshow it can cause some errors

All my drivers are up to date, and my computer doesn't have FFDshow.