garbage collection after loading saved sessions

[elig0n]

Is your feature request related to a problem? Please describe.
I have around 1000 saved sessions.
After the extension is disabled and re-enabled the Extensions memory usage in Firefox Process Manager stays about the same but when opening the extension tab/window when it is loading all the saved sessions up until finished memory usage goes up to 1GB.

If I click GC & CC memory cleaning functions in about:memory the memory gets down again significantly only to go back up once I reload the extension page.

Describe the solution you'd like
Since the extension reloads the saved session with every page restart memory can be cleaned immediately when finished loading all the saved sessions. When I hit GC & CC the memory goes down and loaded tab page keeps working as functioned so I assume there shouldn't be a problem.

Describe alternatives you've considered
removing old sessions