does vim read the whole file into memory

Question

When I open a file, does vim read it all into memory? I experienced significant slowdowns when I open large files. Or is it busy computing something (e.g., line number)?

Answer 1

Disabling features like syntax highlighting, cursorline, line numbers and so on will greatly reduce the load and make Vim snappier in these cases.

There's even a plugin to handle that for you and a Vim tip for some background info.