Post your system specs, specifically i'd like to know your OS, what brand of sound card you are using. From what you said, it's a sound card right?
Not onboard? Is this computer new? Is the sound card new? Everything was working fine
until you updated your sound drivers? If that's not the case, try to think of the last time when everything worked flawlessly, then let me know of any key changes you've done to your pc afterwards. Oh, you said video and sound lags? Monitor your FPS, i want to know if that's dropping to an unplayable/unusual level. If you can see your PC temps, i'd like to know those too, also monitor your processes using ALT+CTRL+DEL, see if any programs in particular are using up a lot of CPU/Memory when this lag occurs.
Things i suggest you do knowing only what you've told me:
-Make sure you have the right sound card drivers, (if you're using a sound card, disable any onboard sound in BIOS) Try rolling back to the old working drivers.
-Update your video card and Motherboard chipset drivers, as well as directx and any critical or recommended windows updates.
-Run a virus scan.
-Make sure all of your cards are all the way in and secured to their respective ports on the motherboard, make sure your ram is compatable with your motherboard and also make sure it's fitted securely.
-Run
Memtest and see if it comes up with any errors.
Hope this helps.