Can i hold 60 fps somehow?

[gladdos]

I want to play Super Smash Bros Meele, i downloaded dophin and everything worked and it was 60 fps, but when stuff get messy ingame it drops to like 35-45, its annoying to play like that..
My specs:

Intel E6300 2,8 GHz Dual Core
4 gigabytes of ram DDR2
And nVidia GTS 250 @ 512mb DDR3

I know that isn't good, but still i thought it could run this perfectly imo.. Could maybe OC for CPU help anything? Im not planning to play 4 player, ik that it requires more, i was planning on playing 1v1 with my brother. Could it be done to be constantly 60 or at least 50 but constantly?

Thanks in advance.