For what it's worth, the real scourge with emacs seems to be people's bloaty config files. I have a fairly small .emacs with maybe five packages to load, takes about 1.2 seconds to open (and finish displaying) on my mac, about .2 seconds on my linux workstation. The editor itself actually starts up much quicker, about 110ms on my mac, 40ms on my workstation. Also, generally I use emacs daemon, so I don't really need to start it up at any point.

I don't tend to open files in excess of 100MiB, or do more than about 20k replaces in a file interactively, so I never really notice latency on operations.