Certain sites very slow

Hello everyone,

I'm relatively new here, so I apologize if this is not the right forum for my question.

In any case, I upgraded to High Sierra recently, and this is an internet related problem. A couple of days ago I noticed that certain websites are very slow, they take 2-3 minutes to load. Others are as usual and load in a few seconds. The websites that are slow are news-related mostly, it also happens with amazon. The situation is the same with all browsers, Chrome, Safari, Opera. I noticed that if I disable javascript then all sites are back to normal. I can't keep it disabled though, since certain sites need it. It must be some javascript related problem, but what exactly? Any ideas?

Thanks