yes, vivaldi is very good, but as it depends on the evolution of chromium, the last update removed the flag Hardware-accelerated video decode and now my vivaldi is again more greedy in cpu for playing videos.
This flag saved me a lot, 15 to 20% of cpu for vivaldi on 720p youtube videos, now around 30%. Firefox stay at 20-30% of cpu, as a result, on my old core2duo samsung laptop now, firefox is less greedy! Who would have believed it? The first time I see that.
(h264ify on both)