Meanwhile, Firefox Sync encrypts your data with a password-derived key so that Mozilla can't even see your browsing history. Consider your choices.
On the other hand, firefox is really sluggish.
> firefox is really sluggish
Statements like this are very hard to quantify in a meaningful way. Especially on Windows, over a time interval I can notice a definite performance degradation of programs. Often times, completely deleting all program data and reinstalling seems to fix the problem. On GNU + Linux and macOS systems, I've noticed that Firefox is usually snappier to render pages.But I wouldn't go so far as to suggest that one browser is sluggish -- there are too many environmental variables to have a good discussion on this subject.