The sound driver game crash bug was widely spread, I even had the problem in the past.
I don't really know why or how the sound driver affects the game that much, but usually updating or disabling the sound driver fixed 80% of the crash bugs.
Concerning the lag in-game, I think that the game is just not effective/efficient in using the better hardware during online gaming. The internet connection is a major factor too. Slow internet connection will more than likely give you lag than aging hardware.
The game hasn't run any smoother after upgrading my Graphic Card from a 8600 GT to GTX 560. Also, the game has difficulties utilizing multiple core CPUs, sometimes one has to dedicate a single core to the game (run like a single core CPU).
You very welcome Col.Hstar.
Cheers
Yanoda