Do games slow down when going splitscreen?

[Xeno Aura]

A 4770k should handle MK:Wii fine.

My cousin uses an i5-4670 which runs MK Wii at a constant 60FPS in 1 and 2 player, and a constant 30FPS in 3 and 4 player.

MK Wii lowers the frame rate from 60 to 30 when in 3 or 4 player modes, so it's actually not as hard to run as you might first assume.

Like Shonumi said, you'd probably have a hard time finding a game that your PC had difficulty running at full speed.