Witcher III PC Hitching Performance Issue

Please watch in 60fps, and note the video really doesn't do the issue justice, it's much worse while playing. The game will sometimes work perfectly for hours, not a single frame drop, no lag, no hitching, no stuttering and then in a blink of an eye it will turn into a choppy mess that constantly hitches. Restarting the game fixes it, but for a few minutes only. I am totally lost on this issue. i5 3570k @ 4.3GHz, GTX 970, 8GB DDR3, SSD, Windows 10