Firefox and Firefox-derivative browsers have and continue to be seriously sluggish and memory and energy hogs. This should not be swept under the rug.
Even today it is difficult for me to use Firefox, Mullvad, etc. When I used to use them, almost every time my machine became slow the solution was to kill Firefox.
EDIT: It's true folks, I would love to be able to use Firefox as my primary browser. But all my experience with it (and I used it for more than a decade) has been dogged by its sluggishness.
I use Firefox mobile pretty much exclusively. I haven't noticed any meaningful performance difference between it & Chrome. It also seems to perform fine on my Fedora laptop.
Mobile is different. I rarely even use mobile. I do however use a lot of tabs on desktop, and Firefox is found very wanting in the performance department.
I don't even think its about number of tabs. Just yesterday and today, Mullvad browser takes minutes to load a set of about 7 pinned tabs (with no other tabs) on startup, whereas Helium (which is based on Chromium) loads in a second or two close to a hundred tabs.
My Firefox currently has 33 tabs open (way more than usual). It opens in seconds on my 9 year old i7-7700k desktop.
Firefox is only sluggish because Chrome uses your data to prefetch pages.
This does not make sense. Firefox would be taking minutes to open a page that Chrome opens within a second or two. And if Chrome was doing aggressive pre-fetching, then it should be using more memory, no? And yet the opposite is the case.
Not denying your experience but if it is taking "minutes" then that sounds like a highly specific glitch that you should try to debug.
Speaking personally I have used Firefox pretty much exclusively for 20+ years, always on low-end hardware. It's been years since I last had any performance issues.