That sounds painful. One of the headline changes in Firefox 48 was that some users have a new feature enabled (e10s), which separates the browser interface process from the page content process. The content process moves into plugin-container.exe. Firefox 49 is expanding the roll-out, so this might cause issues for some users.

Could you confirm that you have this feature turned on? Either:

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, check the row for "Multiprocess Windows" and see whether the number on the left side of the fraction is greater than zero. If so, you are using e10s.

If your Firefox is not performing well with e10s enabled, you could try turning it off here:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste autos and pause while the list is filtered

(3) Double-click the browser.tabs.remote.autostart.2 preference to switch the value from true to false

Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart

At your next Firefox startup, it should run in the traditional way. Let us know if you notice any difference. (It's really a temporary workaround for diagnostic purposes, and not a solution.)

If you are willing to suffer a bit more, a developer has been seeking out people who see the "loading" icon on tabs to help debug the problem. More info in this Reddit thread:

https://www.reddit.com/r/firefox/comments/51t9bi/please_help_me_destroy_the_tab_switch_spinner_on/

Also, it was suggested to make a screen recording in this post: https://www.reddit.com/r/firefox/comments/54fxoj/how_to_remove_the_loading_of_the_page/d81q9uj

Thanks a lot for answering :)

I set the browser.tabs.remote.autostart.2 to false and I'll be looking out for any difference in performance. I'll let you know after a few hours how it turned out.

I'll also check the reddit threads!

Good news and bad news:

The good news is the plugin-container.exe is gone and I can use firefox without getting the loading circle between tabs or the horizontal image breaks I was getting while scrolling or watching videos.

The bad news is I went somewhat deep on facebook (8-9 hs ago posts) and it's still consuming 2GB+ of RAM while on the same cases, before, it always capped at 1,3GB or 1,4GB. But hey, that's manageable by getting more RAM. I'm satisfied for now, :)

It's possible you were using some add-ons or settings before that led to the lower memory footprint and hopefully you'll remember what they were, since the FB news feed generally does consume a ton of memory.