Emacs Opening Large File Slow

While you have a large file, opening the file may be very slow.

The problem is almost always due to font-lock-mode, which does the syntax coloring.

also, linum-mode

You can turn it off by Alt+x global-font-lock-mode and Alt+x global-linum-mode

then, open the file.

Another way to solve the opening large file problem is by using Alt+x find-file-literally. It'll open the file without syntax coloring, and without interpreting Unicode.