Guild Wars 2

Specs:
OS: Windows 7 Ultimate x64
CPU: Core 2 Duo E8400, 3ghz
RAM: 4gb DDR3, 1333mhz
GPU: Sapphire HD5750, OC-ed to 870/1280mhz

Normally, my FPS goes around 25-35 on medium-ish settings, but anytime I enter a group event it goes down to 10-15. Also tried WvW, but this is completely unplayable. My top FPS barely reaches 12 FPS. Lowering the settings doesn’t help either, the performance is the same on low settings as it is on medium.

I am having some sound issues which usually happen after an area transfer or any other map loading event. The problem is the fact that almost every time a new area loads, I can only hear certain sounds, such as the music, fighting, or speech, while other sounds are muted for a certain amount of time. Then, either the sounds get back in a few minutes, or I have to change my sound devices in the options in order to restore them. Anyone got the same issue?

Edit: My sound card is SB Audigy, in case that helps.