Edit with a Apple using Final cut 10 for Gopro and iMovies when i edit with Knoxies panasonic camera footage
Up grade your ram to as much as your computer will take other wise it will give you the fuck around. I went from 4gig to 16gig for no more muck
Or if you have a PC Sony Vegas. The HD version isn't too expensive, the pro version gives easy smooth slow motion but is about 1k. (you can download trial versions to play with) As Mark says, lots of RAM and if you can an SSD drive in ya PC. The more grunt your PC has the easier and quicker the editing is.