Comment 16 for bug 156201

It's much worse than described. It's not just that you don't (and should) see a progress bar, that the whole UI blocks (and shouldn't) and that you don't get a warning when the file actually can't be properly handled.

It's also that handling of big files is ridiculously inefficient.

A file as small as 30MB hangs gedit, takes ages to load, and renders the UI unresponsive every once in a while when trying to scroll it.
I can open the very same file in VIM seamlessly in a fraction of a second and navigate through it. And vim does syntax highlight too.