Does it still happen in Troubleshoot Mode?

Yes unfortunately!

I'm honestly so frustrated by it that I've had to start using Chrome to access it. I don't have the problem on that browser at all.

Does it still happen in a new profile? An easy way to test a new profile is to install Developer Edition and see if it happens there or refresh your existing profile.

Ok so did the refresh but it still shows that slowing down Firefox prompt. I see that prompt in messenger on news feed. opening groups, pages all inside of one tab. In other words I don't have other tabs or windows open.

The other thing is it takes like 3 seconds to show that I can click any of the buttons inside of Facebook such as home screen, a page etc.. Like there is a delay. If I type something it has a delay as well. I dont have these issues on chrome otherwise if I did the I would suspect it would be the computer itself. I'm still gonna do a full scan of my computer for malware etc here in a minute. I will also try the new profile thing here soon.

So I know much about developer stuff honestly. It is happening the developer edition as well. When I click debug script in developer browser it displays 5 errors and 4 warnings. Don't know if its any of these or something else.

Errors: 1 This page uses the non standard property “zoom”. Consider using calc() in the relevant property values

2 WEBGL_debug_renderer_info is deprecated in Firefox and will be removed. Please use RENDERER

3 Partitioned cookie or storage access was provided to [there is a link in this] because it is loaded in the third-party context and dynamic state partitioning is enabled.

4 This page uses the non standard property “zoom”. Consider using calc() in the relevant property values, or using “transform” along with “transform-origin: 0 0” [maw proxy page]

5 Cookie “presence” does not have a proper “SameSite” attribute value. Soon, cookies without the “SameSite” attribute or with an invalid value will be treated as “Lax”. This means that the cookie will no longer be sent in third-party contexts. If your application depends on this cookie being available in such contexts, please add the “SameSite=None“ attribute to it. To know more about the “SameSite“ attribute

Warnings: All of the warnings say Firefox can’t establish a connection to the server 2 which say .edge-chat and 2 gateway.facebook

Firefox can’t establish a connection to the server [gateway.facebook.com/ws/realtime......] was interrupted while the while [link] page was loading. Firefox can’t establish a connection to the server [gateway.facebook.comws/realtime.......] was interrupted while the while [link] page was loading. Firefox can’t establish a connection to the server [edge-chat.facebook.com/chat?......] was interrupted while the while [link] page was loading. Firefox can’t establish a connection to the server [edge-chat.facebook.com/chat?......] was interrupted while the while [link] page was loading.

• Install uBlock Origin to reduce the amount of junk loading.
• Uninstall any third-party antivirus or security software.
• Go to about:third-party in the address bar and block third-party modules.