unfortunately too few setting options or
the setting options offered do little to change the behavior

Sleep Mode is a good idea, don't get me wrong. I've use this extension for a very long time while on Windows and without any problems until now. A few weeks after switching to Kubuntu 23.04 and then to Fedora 38 later, Firefox began crashing almost immediately. Disabling all extensions and re-enabling them one by one in Safe Mode traced the cause of all Firefox-related crashes back to this Sleep Mode extension. Because of this, I cannot in good conscience recommend the Sleep Mode extension to anyone until this fatal bug has been fixed on Linux!

Very usefull... low battery, less energy use... An otpion to automate it on all Windows oppened would be greater. Thanks

The idea of this extension is fantastic! I have it installed since years (it is an older laptop, where RAM is precious) and can see the immense effect of putting the tabs to sleep.
There is still a key point missing to make it consistently powerful: The counter should be applied for each individual tab: When I have e.g. 15 tabs open, 12 may go to sleep, but I am still actively working with 3. But these 3 tabs then have to wake up every time I switch between them - which costs time on machines with little power.

When I installed, all tabs already discarded were loaded. This is fatal.
I recommend extension like "Auto Tab Discard" instead of this.

I grabbed this addon when I saw FF constantly eating up bandwidth when I'm not using it. The good is that this addon solved that issue. The bad is that the timer does not reset itself to the user-defined interval, so the timer is a pointless feature. The ugly is that disabling the addon triggers every tab to reload; that simply should not happen.

Almost but not quite usable.

EDIT: Was looking for a builtin FF setting but instead found Auto Tab Discard. It offers more options and just works.

WOW...WOW...WOW
This is what I have needed all along... Firefox has been killing my cpu, memory and very much my battery... this addon is perfect. you may need to shutdown and turn on your laptop because I did not get any affect until I did this.. you do need to click on the addon and press start!
Truly amazing!!!! my cpu fan is off and I am running a i9 mac and bottom case of the laptop is so cool for the first time I can remember!!!
Thank you thank you thank you!!!

Enabling this add-on activates all currently unloaded/discarded tabs. Firefox immediately tried loading my 200+ unloaded tabs, effectively breaking my session. This add-on also breaks firefox's default restart behavior which is not to load background tabs.

Seems to work, but will also break middle-click / ctrl-click on a link: a tab will open but it won't load and the url is lost, so one can't re-load ):

So far works okay. Has some bugs that need to be ironed out to make the experience smoother.

Would be nice if you could manually put a tab to sleep. Like if I accidently click on an older tab, a right click option to put it back to sleep immediately would be nice. I imagine that would be difficult to do since the tab is already open, so maybe it switches to the next active tab before it does that?

Also, it would be nice if you could edit the sleep duration without having to disable and restart it. Like if I have it set to "Immediately" and then switch to "15 minutes", hitting start won't update it. I have to hit "disable", which then awakes every single tab (and causes a slowdown), before hitting "start". Functionality that updates the timer duration without resetting everything would be nice.

EDIT: Updating the timer doesn't seem to work at all actually. The icon will say "15" for 15 minutes, and the tabs will sleep after 15 minutes, but if I click on one then leave, it immediately goes to sleep.

EDIT #2: It just keeps sleeping my tabs immediately after leaving. This is a deal-breaker if the timer doesn't work. Uninstalling addon for now, may come back in the future.

Very nice. Thanks matico !

Just started using this and set the timer for 0 minutes. The results are remarkably good. I constantly monitor my RAM & CPU usage, and the RAM has dropped by over 50%.

So far I am very impressed.

I was considering dropping the use of Firefox for Chrome, due to its massive memory leak issues. But now I will stay with Firefox a little longer, as Ive used it for 10 years and love all the useful addons.

Only suggestion is make an option to have IE last 2 tabs open. so when i'm working in WordPress and my website, i can switch back and forth between last 2 tabs without a delay in waking them up.

Thanks dude!

Very nice idea. But wish for 2 extra features:
(1) White list. Right now we can only choose to ignore all pin tabs or not. For example, I only want to ignore gmail pin. So a white list will be more flexable.
(2) This is more for desktop and I switch between a lot of tabs. However tabs reload the whole page when activating. This become quite painful. It will be nice to have option to choose the "sleep mode" between suspended(eg. just stop/pause script) and clearing completely(the current way).

This addon is really useful for people like me who open a lot of tabs. it really does reduce ram usage.

However there seem to be some issues still lingering:

1. For some reason opening a new tab from either a hyperlink/image/etc... through right-click/scroll-button, will make the new opened tab, completely blank. the name of the tab is still there, but the page cannot be accessed and since the url is also blank, you pretty much can't do anything. This is really annoying and needs to be looked at

2. there are times when my browser is stuck and i can't do anything. The best example i can give is when i turn off the addon while a bunch of tabs are open.
This needs to be adressed as well

3. Could i get more explanation on the whole pinned tabs? how do i do that?

Could you add an option to set a delay for when the tabs go to sleep?