Please don't tack onto unrelated support threads. I have made yours a separate post.
There isn't enough detail in your post to determine what the cause might be. If this occurs generally on all sites, I don't have a solution for you. If it occurs on specific sites, there might be something that can be looked at.
Please note this assumes you have done all the low-hanging fruit already such as turning on basic adblock, eliminating unnecessary add-ons and seeing if a profile reset makes the problem better.