My experience: on 32bit single core computers (even with fast processors) it is never a good idea to start videos in browsers directly. Use a dedicated video player program instead, which makes use of hardware acceleration from your GPU, while browser will use CPU instead in most cases.
But even then: Some videos will have resolution requests your equipment will not be able to play judder free, even in dedicated player. Solution: download items in e.g. youtube-dl with reduced resolution.
Check available resolutions first: youtube-dl -F '<URL>'
This displays all available formats.
Chose one video format and one audio format. For audio you can always chose the very best you can find, since this will rarely max out your device. From Video format chose what your equipment is just able to display judder free. Combine the format numbers like e.g. youtube-dl -f '(136+251)' '<URL>'
First number representing videostream, second representing audiostream. Streams will get merged automatically again and you can play them judder free even on extremely weak hardware like prehistoric 486 CPUs.
This combination of 1) searching for video streams with https://invidiou.site/feed/trending and 2) viewing with mpv works very good for me. Uses very little resources, which is what I was wanting. I am going to adopt this approach.
Thank you all for your suggestions. Now I don’t have to install all those fancy browsers. I will stick with firefox-esr and chromium as my main browsers and use mpv and that invidiou web site for search for streams.