The consensus seems to be that Atom is still much slower than ST3; I'm still on ST2, and I find it terrible for opening large files and mostly resort to Emacs for that sort of task (and anything involving search and replace with regular expressions on even moderately-sized files). Is ST3 markedly faster than ST2 and generally worth upgrading to now?

(I've held off upgrading because I've always been in the middle of a project... but I'm now realising that I really am just always in the middle of a project, so I might as well just get it over with.)