Sorry to say that, but about:memory is useless to me. When memory runs low and system starts swapping (slowing down to a crawl) my first priority is to get computer running again, so I have to close firefox. That helps, but about:memory no longer has the data that would lead to the culprit.
Even if I could look at histotic data, the UI of about:memory is just plain awful. Charts anyone? My main question is how the consumption of memory for each tab is changing through time and I haven't found a nice way to see that yet.
Also, browser should protect me from pages which use too many resources. Why should some random page be able to stop my computer from working? I am seriously considering running firefox inside docker container just so I can limit its resources.
Note that I am a huge fan of ff and use it everywhere, but this has been a sore point for me for ages.