Windows is a virus

Against my better judgment, I installed Parallels on my new school MacBook Pro. I just uninstalled it. The machine was running slower than I do on a cold morning and getting slower faster than I am with age. The hard drive was running constantly. My available space got down to 116KB (from 14 gigs). Something in Parallels or Windows was running on its own and filling up space; I’ve seen on the forums that I’m not alone. It’s gone. My machine is back to normal, I hope. Windows is a virus.