MicroT :
Try clearing your browser, cookies etc. and if that doesnt help try resetting your browser both chrome and firefox have this in there settings. I dont recommend using anything other than these two browsers as they are the most reliable from my experience
Tried that, both has the same problem.
schwatzz :
Which websites does this occur on? What is the speed you get from your ISP?
I tried Youtube and Dailymotion, both has the same issue. and I get 30
I also noticed that when it comes to 60fps videos It's smooth, the problem is on videos that are'nt 60fps even though they are 720/1080p