The video / photo adds at the bottom only activate if you click on them.
First, make sure that your o/s is up to date (most current release(s))
Second, make sure your search engine is up to date (most current release(s)).
Third, make sure your anti virus is up to date (most current releases).
Fourth, your over the top computer is also some of the problem because of it super abilities to multitask.
Fifth, the Pop-up Add pushers, uses your multitasking computer to push through their add(s). Most commonly voice / music. At the point that the Forums software is linking between your laptop and its server you see the slow down, freeze-up.
As long as the search engine people sell access to these groups, it will be an on-going fight.
I'm working with my anti virus supplier at least every other month. Forum based systems are very exposed to this type of problem because the the near ongoing interaction between your laptop and their server.