A combination of stuttering and lag
It seems that no matter whether you have the best of the best in PC hardware, it is no match for the stuttering and lag issues that buyers of the PC version of Call of Duty: Black Ops are experiencing. As the number of reports and unhappy PC players of the title continue to grow, the developers at Treyarch continue to try to determine a course of corrective action to resolve the issue.
The lag seems to be more pronounced in the multiplayer modes, while the stuttering issues that max out the CPU seem to be worst in the moments in the game with the least amount of action or in the cut scenes, for example. Speculation seems to be that a memory leak might be the problem, but so far that is just speculation from what users are reporting.
Treyarch has not officially responded to the complaints, but some forum posts confirm that they are aware of the issue and are working on the problem. At this point there continues to be no official word of when to expect a patch, but we believe that they are working on one.
The reported PC server browser issues that seemed to have been a problem right at launch have apparently been resolved by some server side adjustments, according to the whispers that we hear.