I'm playing Black Ops on PC, and have been having some problems. Random performance issues, even stuttering during cutscenes. Turns out I'm far from the only one.
Many PC players are reporting issues with the game related to poor performance that has nothing to do with their own hardware. For example, Black Ops will slow to a crawl in relatively quiet areas of the game, while in hectic stages full of explosions it may carry on just fine.
This issue is affecting users in multiplayer as well, creating the effect of "lag" when in reality the best theories out there point to it actually being a memory leak.
The pic above shows an example, the game taking up a dangerous (and ridiculous) 85% of a user's CPU power.
There's no confirmation yet from developers Treyarch on the cause or a possible fix for the issue.