Firefox installations quickly got slow and bad. Profiles became corrupt. Third party software installed toolbars that were difficult (or impossible, in some cas

Firefox installations quickly got slow and bad. Profiles became corrupt. Third party software installed toolbars that were difficult (or impossible, in some cases) to remove. It wasn't until fairly recently that Mozilla stopped third parties from sideloading crapware extensions. Firefox dev tools got slow to the point of unusability and lacked critical features (e.g., almost anything related to websockets). Standards support lagged far behind. When Gary Kovacs shifted the focus to Firefox OS, the desktop browser lost pretty much any advantage it once had.