high cpu usage streaming content

Hi,

I have a MacBook Pro 15-inch early 2011 (MacOs High Sierra 10.13.2) and I have a problem every time I want to see a streaming movie and I start the video on a site like openload, wstream, streamgo ecc : on Safari after a few minutes the CPU usage goes high and it reaches up 700%. The same thing happens even if I change browser, for example Chrome. Any ideas?

Thanks