It's not well-explained in this article, but the problem is that when press a key like O in normal mode (to insert a line), vim will wait a certain amount of time to see if there's another key of a sequence about to follow. Reducing this timeout or disabling esckeys will reduce the or eliminate the wait time.
And, if you remap Caps Lock to Ctrl, Ctrl-C will be easier to type.
This works 99% of the time. The only exception I know of where it performs differently is in operations on a visual block (not visual line) selection -- hitting Ctrl-C only applies changes to the current line but Esc does what you want.