Although the relevant links have already been provided, the gist is

• Acme stands for some "generic" editor here, where you have to use the mouse a lot, which is perceived as slow
• Emacs is known to be very powerful (to the extend of being called an "OS with a bad editor"), but using unergonomic keyboard shortcuts
• Vim is an editor that has been designed for keyboard power users in mind, but which has the reputation of being difficult to learn