I use FF too, and I notice it sucking periodically, often after a big update - as things will - there have been periods of a month maybe two times in the last 10 years where I had to switch to another browser because it sucked too bad.
Sadly this is my story also. I use Vivaldi as my main browser now, which is Chromium based. Firefox does work awesome and is normally what I program my scripts through headlessly but in personal use FF just gets bad periodically.
