In the absence of any meaningful information that could help us to help you, search for maxfpsbk. If you're CPU bound, that and maxfps will almost certainly help.

If, after setting maxfps/maxfpsbk to reasonable values you still have problems then post more of your system details (number of cores, number of monitors, OS, etc) and tell us what observations you are able to make when you run both WoWs.

Of most interest would be whether you are CPU-bound or memory constrained.

As for your assertion that the Wiki fails to provide you with enough information on how to create two copies of WoW, and that it "is useless" (quoted from the title of your other post), you are quite wrong. It works for everybody else just by following those steps.

If it didn't work for you, either you did something wrong or there's "something else" going on here that only affects you. It does not imply any lack of clarity in the Wiki, and it certainly does not imply that the Wiki article is in any way useless.

In fact, you're generally likely to get better responses if you can manage to phrase your questions in less emotive terms, even in the face of the obvious frustration you feel at being unable to get even something as simple as a dual installation of WoW going.