That's a really tough problem to solve on Linux. We're actively working on it in order to make Firefox better behaved when memory gets tight but it's not easy. You can follow the work in these two bugs:https://bugzilla.mozilla.org/show_bug.cgi?id=1532955
https://bugzilla.mozilla.org/show_bug.cgi?id=1587762
heavyset_go|4 years ago