Another clue that I have seen is that Firefox has been reporting a negative value for the heap-texture memory use. I don't know if this indicates a bug in Firefox's managing of that memory, it's reporting of that memory, or of Xorg's managing of that memory which is just being exposed by Firefox. I have noticed that Xorg's memory does grow even when Firefox is not running as shown in the idle logs in my original post. I haven't been able to keep the computer idle for more than a day to see how bad the problem gets in that situation.
3,530.59 MB (100.0%) -- explicit ├──2,136.22 MB (60.51%) -- window-objects │ ├────958.44 MB (27.15%) ++ top(<anonymized-1851>, id=1851) │ ├────673.34 MB (19.07%) ++ (429 tiny) │ ├────177.67 MB (05.03%) ++ top(none) │ ├────138.30 MB (03.92%) ++ top(<anonymized-3408>, id=3408) │ ├─────97.81 MB (02.77%) ++ top(<anonymized-2247>, id=2247) │ ├─────47.99 MB (01.36%) ++ top(<anonymized-2725>, id=2725) │ └─────42.67 MB (01.21%) ++ top(<anonymized-728>, id=728) ├──1,862.17 MB (52.74%) ── heap-unclassified ├────494.26 MB (14.00%) ++ js-non-window ├─────96.45 MB (02.73%) ++ heap-overhead ├─────43.69 MB (01.24%) ++ xpconnect └──-1,102.20 MB (-31.22%) -- (22 tiny) [?!] ├──────29.89 MB (00.85%) ++ workers ├──────27.46 MB (00.78%) ++ images ├──────22.72 MB (00.64%) ++ atom-tables ├──────20.70 MB (00.59%) ++ storage ├──────17.34 MB (00.49%) ++ media ├──────17.15 MB (00.49%) ++ add-ons ├──────12.33 MB (00.35%) ++ network ├───────7.98 MB (00.23%) ++ dom ├───────2.25 MB (00.06%) ++ cycle-collector ├───────1.79 MB (00.05%) ++ layout ├───────1.03 MB (00.03%) ── xpti-working-set ├───────0.72 MB (00.02%) ── cookie-service ├───────0.69 MB (00.02%) ── history-links-hashtable ├───────0.58 MB (00.02%) ── preferences ├───────0.51 MB (00.01%) ++ xpcom ├───────0.45 MB (00.01%) ── icu ├───────0.43 MB (00.01%) ++ webgl ├───────0.34 MB (00.01%) ── telemetry ├───────0.26 MB (00.01%) ++ startup-cache ├───────0.13 MB (00.00%) ── script-namespace-manager ├───────0.00 MB (00.00%) ── spell-check └──-1,266.96 MB (-35.89%) -- gfx [?!] ├───────7.95 MB (00.23%) ── font-shaped-words ├───────0.42 MB (00.01%) ── font-tables ├───────0.26 MB (00.01%) ── font-cache ├───────0.09 MB (00.00%) ── font-list ├───────0.08 MB (00.00%) ── font-charmaps └──-1,275.77 MB (-36.13%) ── heap-textures [?!]
