In general, editing large files in Emacs is super-fast. What's NOT super-fast is editing files with super-long lines (it doesn't even have to be a "big" file).

In general, editing large files in Emacs is super-fast. What's NOT super-fast is editing files with super-long lines (it doesn't even have to be a "big" file). For whatever technical reason, that can grind Emacs to a halt. I'd love to see that bug fixed myself.