I have a very similar background with Firefox / Firebug and Vimperator, but there was a period where - despite all JS benchmarks seemingly proving otherwise - C

I have a very similar background with Firefox / Firebug and Vimperator, but there was a period where - despite all JS benchmarks seemingly proving otherwise - Chrome's real / perceived performance completely blew FF out of the water. Specifically things like startup time, opening a new window or tearing a tab off one, time to first content displayed when clicking a link, etc. As a result from about 2011 to 2017, I kept periodically checking back with FF, but was effectively a Chrome convert (Vimium was a good enough replacement for Vimperator). Once Servo hit the FF mainstream, it immediately felt faster, and I switched back. I still find myself switching back to Chrome for web dev debugging, probably for familiarity reasons. In this sense though, I'm sure I'm not the only one for whom "Firefox is back".