find parameter Override software rendering list. Choose Enabled ! Done!
"Overrides the built-in software rendering list and enables GPU-acceleration on unsupported system configurations."
Now the video 1080p/60fps on Twitch and 1440p on Youtube runs smoothly and without interruption.
My PC: Amd Athlon II x3 445, 6 Gb RAM, Radeon HD 7790 1Gb
this helped a lot, but consequently left all the images blurry, but at least I can watch twitch in 1080p60 without consuming too much cpu, and I can also disable it when not watching twitch, thanks