I switched to Firefox in the end of 2019, and I don't think it's entirely clear cut, slowness-wise.
In my experience, Safari slows down to a crawl if I open more than 5 or 6 tabs at once, especially something sadness inducing (think new reddit); and it's very eager to.. dump things from memory? I am not sure what happens, but as I switch these gargantuan tabs, it seems to re-draw things a lot.
Firefox handles that kind of thing like a champ. Add uBlock origin, and I have my almost ultimate browsing experience: JavaScript off default, enabled as I see fit.
There is one nasty oddity where I often found myself having to slow down for Safari: when I edit URL query parameters. If I hit return before some indecipherable arbitrary time, which I guesstimate by the auto completions showing up, Safari will throw away my changes and merely reload the current page. I have unchecked and toggled all possible autofill or search checkboxes in Safari settings, and it still happens. This and the extension apocalypse are what drove me away from Safari. In contrast, I've got all the extensions I want, and never ever have to slow down for Firefox.
Well worth giving it a shot for a few weeks. Container tabs are also awesome.
Why is Firefox slower on a Mac? I know Safari is (supposedly) faster than a lot of the other options, but I haven’t seen anything about Apple slowing down other browsers on Macs[0].
[0] I know they force all browsers to use the same webkit engine as Safari on mobile devices, and used to limit competitors to an older slower version for “security reasons” but AFAIK they don’t slow down competitors on mobile anymore and never have on Macs
It's not Apple that slows down Firefox on Mac. It's just that Firefox cannot match the resources that apple and google throw around on their browsers. Firefox has to be economical on where their resources are directed towards. And understandingly Macos specific optimizations not the top priority.
Firefox natively suspends unused tabs which dramatically improved my memory usage and battery life.
Chrome has a similar extension but it's nice having it built in to the browser natively.
If anything you could argue that FF is behind Chrome security-wise with their more limited sandboxing and some other memory protections. But performance is largely a non-issue.
Understandable from perspective of how apps are developed, but from the user perspective comparing Firefox on Mac to Safari on Mac is literally comparing software on Apples to software on Apples.
