Earlier quoted context omitted.
I'm amazed. What browser do you use? Firefox is flying by really well (that too on a Core i3 5th gen + NVIDIA 920m with 8GB RAM). This sounds nuts.
I'm on Ubuntu with Google Chrome.
I think it could be some issue with hardware acceleration then? The link is a bit old so I don't know if things are still the same, but I used this long ago.
http://www.webupd8.org/2014/01/enable-hardware-acceleration-...