Wireless has a long inherent latency. As I remember it you can generally expect 20 ms or so extra latency on top of what you would get with a wire. If possible I'd definitely try using a wire to see if it fixes the problem.

You might also want to see if this helps:
Reducing latency

If you are running 5 copies of WoW on your machine the extra 20 ms delay from wireless would be multipled by 5 (potentially, ymmv).