Re: The title is no longer required.
firefox with noscript on all of the time works for blocking nearly all of the ad/tracker crap. And in those rare cases where I _MUST_ do something "scripty" I do the following (on a FreeBSD or Linux machine).
1. make sure I've run Xorg with the -listen_tcp option [or some equivalent thereof]. This is sort of required for me, because I like to do embedded dev across a network, and not even try to use a tiny screen like for an RPi as a development platform...
2. xhost +localhost (naturally) - this lets you connect from localhost.
3. from a terminal on the desktop, 'su - otheruser' where 'otheruser' is as guest level as you can make it
4. in the shell as 'otheruser' export DISPLAY=localhost:0.0
5. then 'firefox http://whatever/ &' as 'otheruser'
7. make sure the browser DESTROYS ALL HISTORY ON EXIT, from cookies to cache, and especially passwords
this has no obvious performance (or other) issues when playing videos, or doing anything ELSE the browser needs to do, in order to properly display any content, access any web service, etc.
Yeah, FreeBSD and Linux (with Xorg, *NOT* Wayland) are AWESOME in being able to share the desktop like this and run in the context of a user that doesn't have any cached info on what you've been doing...