R2TW is more CPU intensive than most games and scales well with OC'ing. If you dip into the
benchmark thread, you can get an idea of how much a difference an OC makes.
Intel Core i5-3570K @
4.2 GHz, Ivy Bridge, 22nm lithography, 67 Watts TDP, DDR3 1600 MHz CL9-9-9-27, Dual Channel: 36 FPS
Intel Core i5-3570K @
4.5 GHz, Ivy Bridge, 22nm lithography, 67 Watts TDP, DDR3 1600 MHz CL9-9-9-27, Dual Channel: 41 FPS (13.8% increase)
Granted that's only the CPU benchmark. When factoring in your GPU, I think that's something you should test yourself.