In my experience, it's negligible. There will be lag but not the kind that makes you wait for something to happen after you have pressed a button. Actions that

In my experience, it's negligible. There will be lag but not the kind that makes you wait for something to happen after you have pressed a button. Actions that require a lot of redrawing tend to lag, though: if you only know `hjkl` navigation and visually select every string you want to work on you will definetely experience some lag. On the other hand, if you use more "advanced" movements and use text-objects and Ex commands extensively, you won't find reasons to complain.