Sleep Mode is a new extension of the Firefox browser, which disables all tabs other than the active tab. In this way, it frees up memory, saves battery and can accelerate the other functions.
Firefox users who like to open multiple tabs, have certainly noticed that memory usage is rising rapidly. Depending on the available resources of each computer, especially in the memory and battery, users can see from continuous crashes to slow down operations.
Third-party tools and browser extensions can help with automatic, semi-automatic or manual processing of Firefox's memory usage. But because of all these extensions, Firefox has not gone through a brave upgrade designed to improve memory usage.
The new Firefox 67 may be able to automatically suspend tabs you don't see, as Google Chrome already does from 2015.
The Sleep Mode is a simple extension which in some cases is particularly beneficial. The extension adds an icon to the main Firefox toolbar, which you can interact with during installation.
The icon works as a toggle key. One click starts the sleep mode. Any tab, in addition to the active tab and tabs that are not fully loaded or not, will be put into sleep mode to free up memory and improve power consumption and system performance.
Sleep Mode removes the site from memory and adds the word "Sleep Mode" to the beginning of the web page title. This feature, depending on how many tabs you have opened, can hide the entire title of the page, making it difficult to identify each page.
With another click on the Sleep Mode icon, Firefox returns to normal mode. All unloaded sites are not reloaded. You may need to go to some tabs to complete the loading process.
So far, third-party extensions are the only way to reduce memory usage in Firefox. Although it looks like we are expecting big changes with the arrival of Firefox 67 on 14 May 2019 on the fixed channel, which is currently available at Firefox Nightly. We already know that we will see changes in terms of memory usage, such as memory unloading for tabs with audio playback, but also changes in security such as ban on extensions to private windows.