After finally discovering why gaming performance was so bad with the Crimson drivers (massive downclocks, rectified with ClockBlocker), I now find that 4K videos run terribly. They stutter like crazy; sometimes coming to a complete stop, and are littered with compression artifacts. When using the Catalyst drivers, I was able to run any 4K content without a problem, including 60 fps files. Now, they are effectively slideshows.
I've checked the video settings in the Crimson application, thinking that maybe some enhancements were causing performance problems, but nothing is turned on. After switching between drivers many times before finally getting Crimson to work nicely with games, I'd really prefer that I didn't have to switch back to Catalyst.
Has anyone else experienced this problem? I believe all the videos I've tried are using the H.264 codec.