From my understanding, overclocking the Genesis would make the overall's game speed faster, but would not resolve the occasional slowdown. I could also imagine there'll be issues with the music going too fast.
This is not like a Windows Computer, where you can fix everything with just having your hardware running faster.
I think, the gameplay speed on most consoles is depandant on the system's clock speed. Just like in those very, very old DOS games, where some of them ran faster overall up to an unbearable speed on modern machines, thus those old PCs had the "Turbo" button to halve the clock speed manually.