Youtube still have problems with VP9 codec, you don't fix it. This is with the new driver.
Framedrops, low gpu usage, high cpu usage. The video was watch at 4K 60 FPS but I record mine at 1080P 60 FPS with ReLive.
I'm using a RX480 8GB Gaming X from MSI and I5 4690K at 4.4 Ghz with SSD. Google Chrome 64 bits last version, Windows 10 Pro.
What I can do? Waiting again? Wait for VEGA? LOL, not... serious, I buy NVIDIA next time.
I record a video for you AMD: