[quote="smallhagrid":15wjuwsb]Endtasking FF for this is excessive, and:
[quote="grr":15wjuwsb]Yes, that is very normal & expected behavior of Firefox. Id do run into similar situation and end-task & then restart Firefox to regain RAM. [/quote:15wjuwsb]

In the portable version leaves behind undesirable detritus which then must be found/cleaned.

Much easier/cleaner ways exist. For example:
[url:15wjuwsb]https://addons.mozilla.org/en-us/firefox/addon/memory-restart/[/url:15wjuwsb]

[quote:15wjuwsb]Memory Restart is an open-source Firefox add-on that allows you to quickly restart Firefox if memory usage is too high. Firefox users can see the memory usage in the add-on bar or the toolbar tool-tip. If memory usage reaches a certain threshold, the add-on bar display and the toolbar icon will turn red. You can quickly restart Firefox at any time by clicking on the add-on bar display or the toolbar icon.

The memory threshold and add-on bar text colors are customizable. There is also an auto restart feature.[/quote:15wjuwsb]

Version 1.1 is the most recent fully functional, newer ones have bugs:
[url:15wjuwsb]https://addons.mozilla.org/firefox/downloads/file/102921/memory_restart-1.1-fx.xpi?src=version-history[/url:15wjuwsb]

Best Wishes.[/quote:15wjuwsb]

Thanks smallhagrid for suggesting this addon.