FPS drop/lagg whenever i aim down sights?

Title, this usually happens when i aim down sights when im looking at alot of player generated buildings… but happens quite a lot, especially in pvp situations which makes it hard because i wont be able to move while aiming in for like 2 seconds.

any help??

tried opening dxdiag and its saying there was a problem accessing directsound, could that be related??

pc specs:
i5-2500k
8gb ram
either 6850 or 6870, cant open dxdiag to find out, and cant remember :confused:

-nothings overclocked