Firefox 117.0 is very slow on startup sometimes taking several minutes. It also uses a lot of resources. I like this browser and really don't want to move to Chrome as my primary browser but, if you don't fix this, I might have to.
I hope someone reads this.
It's not only the startup that's corrup with this update. On Mac, when Firefox is closed (not minimised), clicking a link in any other app (Outlook, Word etc) starts Firefox but not the link to the webpage. So you need to click it twice now. Very annoying. Previously it opened two tabs instead of the one you want. Please fix these issues, in the meantime I switch to Safari.
I still prefer Firefox over Chrome or Safari as it allows to control cookies much better (e.g. selectively keep the ones for two-factor login). If you are on Mac and use Timemachine, you are in luck: you can restore Firefox to an earlier version, for me 115.0.2 (as this was before I went on holidays). You lose your profile and bookmarks, but that's easily restored by synchronising with your Firefox account (if you have one) or from another browser, apart from some settings and managed cookies. When you fire up Firefox first time, do it without any internet connection and then untick the automated update, that lets you keep the older version. At least until those hiccups are resolved...