|The best thing you can do with superfetch is leave it alone - there is a lot of nonsense out there on the internet. If it improved your problem then it was pure coincidence. It is there to help.|
There is no good reason to mess with the swap file either (I assume that's what you meant).
Adding RAM can be worthwhile but not to cure the issue you are having.
Johnr (response #1) is right. It might simply be that the website or internet is overloaded - it is getting worse lately. Try it outside of social hours and see if it is any better.
What you have been doing is like fixing the washing machine when the car won't go LOL. If offline video's run OK then it is kinda telling you something.
Always pop back and let us know the outcome - thanks