I updated to new AMD drivers about 2 weeks ago and instantly started getting issues with stuttering or frame buffering or something (I don't know all the fandancy words to describe this crap.). In Hawken on low graphics/low textures and no physx i was getting an extremely variable framerate from 20-80 FPS; this was using the stat fps thing. Streaming or recording had little effect on the crap framerate since it was so crap anyway.
Yesterday I rolled back my drivers. and BOOM 120-140 FPS. Streamed at 720 30 FPS, faster encoding, 2200 bitrate and it never dipped below 100 frames.
Moral of the story: AMD's new driver is probably designed for their r9 3xx series and Windows 10 or something and fuzzy bunnyed up my 290 on win8.1.