I have noticed no performance decrease, im fact, some of the games that utilize open ati drivers ran even smoother on linux with my radeon gpu (like pillars of eternity). If you're unsure, you csn always just coinstall some linux distro (i went for manjaro/gnome, super smooth experience and rolling updates), and just boot back and uninstall linux if you're not satisfied. I used have dual boot too 'just in case' amd it was preinstalled om mh notebook anyways, but last time i have logged into windows was about 6 months ago and now i even forgot i have it. With older games it's actually a no brainer because Wine never failed to run any game that did not have a native linux port too