Why won't Minecraft Open?

I have a modded single player 1.5.2 minecraft world on my mac and it's way to slow so I copied the minecraft folder onto my PC and put it in windows roaming and renamed it.minecraft and the launcher looked like it was working since it had forge and I was signed in but when I hit "Play" nothing happened. I waited about 20 min. Before exiting and retrying several times and the same thing happened all the times. I know my PC can handle minecraft but is the fact the the folder is from mac mean anything? Do I have to go in and change something? Is transferring a.minecraft file from mac to PC even possible? Any answers are appreciated!

It will load… It will prob take days cuz your pc is slow

I'd recommend just copying over the save folder for the world only, if you want to keep it, and get a clean install on your PC, re-installing any mods you previously had.
It may not be the easiest way, but it's the closest you can get to a guaranteed solution.