Windows 10 creators update - Youtube slow in opera with hardware acceleration activated.
There's not much more to it. For example when i wanted to enter fullscreen mode in youtube the screen was just black for a few seconds. After disabling hardware acceleration in the opera settings my issue resolved itself.
What graphics card are you using? Are drivers for it the latest version? My GPU in AMD E-450 APU is blocked with GPU blacklist for reasons unknown, but when I dismiss the blocklist, acceleration of webpages, Youtube, Netflix and others work perfectly.