For those of you who have 8 cores (4 physical + 4 hyper) here is a cool chart to use http://wikizap.mobi/enwow/CVar_processAffinityMask

It also reflects 4 cores. And with affinity set at 15 forces the OS to use 4 cores per client. Even if you are soloing, setting the affinity to 15 will allow you to see some boost in fps.

Drommon