Firefox's performance settings

Firefox automatically uses settings that work best with your computer. You can modify these settings in your Firefox Settings page. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings. In the General panel, go down to the Performance section and uncheck the box next to Use recommended performance settings. You will then be able to change the following settings:

Use hardware acceleration when available: This setting allows Firefox to use your computer's graphics processor, if possible, instead of the main processor, to display graphics-heavy web content such as videos or games. This frees up resources on your computer, so it can run other applications, like Firefox, faster. This box is checked by default, but the feature isn't available for all graphics processors. You must restart Firefox after changing this setting, before it will take effect.

Content process limit: With Multiprocess Firefox, also called electrolysis or e10s , Firefox runs web content for all tabs separately from the main Firefox process for increased security and performance. Using multiple content processes can further increase performance and minimize the impact of content process crashes. You can modify this setting to increase or decrease the content process limit.

The recommended maximum is four but you can set up to seveneight content processes; however, having too many content processes can slow down your computer, and consequently, Firefox.You can set between one and eight content processes. The default is eight. Having more content processes can improve performance when using multiple tabs but it will also use more memory. You can reduce the number of content processes if your computer is running out of memory.