When Firefox Quantum was launched everybody praised it as the next best thing (browser).
But if you look closelly you will only see modest speed improvements into the browser. HOWEVER, you will see massive slowdowns in Windows. At least I did in mine. Why because instead of taking 600-900MB for regular browsing the new Firefox takes not 2GB!
This is because a thing called “multi-process Firefox” was activated by default. The multi-process was suposed to make Firefox more stable. However, it also makes the browser much much larger.
So, how do you make Firefox behave? You disable multi-process:
1. Type “about:config” in Firefox Address bar (where you enter the address of a website).
2. Do a search for “browser.tabs.remote.autostart”
3. Disable it.
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More gory details about this here:
https://www.ghacks.net/2016/07/22/multi-process-firefox/
TLDR