I don&#x27;t even know how it&#x27;s possible that the performance degrades over time as it does, but it has become bad, at least on Linux.<p>Opening the dev tools has such a huge performance impact these days (on an i7 with 16GB RAM and an SSD...) that I mostly don&#x27;t bother to develop with Firefox anymore.<p>Let alone missing features like user agent spoofing, which still requires an addon, or the bug that messes up file associations with every update.<p>I hope they do less UI changes, get their shit together and improve the core.