In many games it does make sense to update th GUI on every frame. E.g. if you have a minimap you will need to update that every frame during which the player is

In many games it does make sense to update th GUI on every frame. E.g. if you have a minimap you will need to update that every frame during which the player is moving. Updating every frame also solves the issue of the GUI updates not being synchronized with screen refreshes (v-sync). You could do something like use event driven programming to draw the GUI to a buffer off screen, and layer that on top of the main render. But that's probably about as intensive as drawing the UI, and more memory intensive.