I'm experiencing a severe performance regression with firefox 76.0.1 installed from the repo. The same version binary download from the mozilla website works as expected.
Yeah we know, and hopefully it's just temporary. Check the message here: R755:7201f61e9be5ac1244d7c21a3f38e7e2561ccdbe
FWIW I gotta say that I didn't notice any slowdowns, but YMMV.
Edit: actually, could you say where exactly you had regressions? Maybe they're unrelated to the commit I linked.