Have you compared it to other browsers? What distro do you use? I've benchmarked performance on Arch, Fedora, Debian and Ubuntu and found that Firefox was 2-3x slower than most chrome forks.
I use Brave on Android for websites that don't work in Firefox. It's probably faster but I don't care. I care more about the difference between 10 and 100 ms (all browsers are not great at general responsiveness) than between 1300 and 1800 ms.
I also use Microsoft Edge on Linux for Teams video calls and can't say that I notice an appreciable difference in performance.
Slower may be true, but is it slow to you? Are you actively loading hundreds of web pages and need Firefox to be that much faster for them?
Maybe it's just because I live far away from host servers that aren't from local companies, but real world latency between your machine and the web server is IMO more important than the browser loading a page 200ms faster than another.
