High CPU usage on Mac OSX

Hi , would you be able to point me to instructions on how to use the t.MaxFps to limit the UI refresh? I’m also having the extremely disappointing problem of high CPU usage when idle (even with realtime off), as it completely determines whether I can continue my subscription or not… Thank you, .

Specs:
PC - Win 7 Pro - i7 3.5GHz - 2x 3GB GeForce GTX 780