Loaded Tabs Limiter by Shajirr

This addon keeps the number of currently loaded tabs below a specified limit, preventing a situation when there are too many loaded tabs eating RAM for no reason.

Usage instructions

• Clicking the addon icon opens a popup menu where you can enable/disable the addon, go to the Options menu, or execute various commands
• Another way to open the Options menu is to right click the addon icon -> "Options"
• Addon icon shows the number of currently loaded tabs that are eligible for discard based on user settings, background colour changes depending on how close it is to the limit
• You can mark a tab as persistent, so that it won't be unloaded by this addon - activate said tab, then right click anywhere on the page background -> Loaded Tabs Limiter" -> Make this tab persistent". There are 2 variants of this command - 'session', which will only save persistent status for current session, and 'permanently', which saves status to storage, so it persists after browser restarts.
• You can add the domain of the current tab to exclusions list - then any tab matching the same domain will not be unloaded. To do so, right click anywhere on the page background -> Loaded Tabs Limiter -> Keep this domain loaded.
• You can manually open a link in a discarded tab - right click on a link and select the option "Open Link in New Unloaded Tab"

Options

• Loaded Tabs Limit - max number of tabs that can be in a loaded state
• Count persistent tabs towards limit - by default, persistent tabs are not counted, so you can have a max number of regular loaded tabs as defined in the "Loaded Tabs Limit" plus any number of persistent tabs. With this option enabled, persistent tabs are counted towards the "Loaded Tabs Limit" too
• Enable timer-based unloading - will automatically discard tabs after the set tab inactivity timeout
• Tab Inactivity Timeout - the amount of time before an inactive tab is discarded
• Check Interval - how often the extension checks for inactive tabs. If your timeout is high, you can increase this interval to reduce the number of checks performed
• Unload pinned tabs - if enabled, pinned tabs will be unloaded too, by default they are skipped
• Unload tabs playing audio / video - if enabled, these tabs will be unloaded too, by default they are skipped
• Domain exclusions - tabs matching any domains from this list won't be unloaded.
  You can add new or delete existing entries.
• Discard pinned tabs on browser startup - self-explanatory. Firefox has a flag for this, but the last time I checked, it doesn't work on Windows due to the bug that Mozilla refuses to fix for years for some reason.

Manual discard commands available via popup menu and keyboard shortcuts:

• Discard current tab
• Discard other tabs in current group
• Discard other tabs in current container
• Discard other tabs in this window
• Discard tabs in other windows
• Discard all other tabs

Keyboard shortcuts need to be set in the "Manage Extension Shortcuts" menu, which you can activate after clicking the gear icon on "about:addons" page.