I've been playing Prototype 2 on my AMD R9 280x using the AMD 14.4 GPU driver and I've been encountering a huge performance dip after 15 to 30 minutes of gameplay - the performance dip how ever gradually fades away after 20 minutes and the game starts to run very well again at 60 FPS with Vsync on, but after 5 to 10 minutes, the game crashes. This gave me the impression that the rumors I heard about AMD having terrible drivers were true - not until now - AMD just released their 14.9 GPU Driver and it has somehow fixed the Prototype 2 PC dilemma. I'll keep in touch if they're still other problems.
Update: The game crashed after 1 hour using the AMD 14.9 GPU Driver.
http://pcgamingwiki.com/wiki/Prototype_2#Performance_degrades_over_time
Always check PC gaming Wiki.