[mort96]

I agree that this is not a necessary downside to immediate mode GUIs, but we're talking about egui specifically here. AFAIK, egui always redraws at some relatively high rate even when nothing is happening. (I'm having trouble finding documentation about what that rate is though.)

[Boxxed]

That's not true, it only re-renders if there's an input event or an animation running. This is very easy to see if you just put a `println!` in your UI logic.

This is also mentioned in the gui docs here https://github.com/emilk/egui#why-immediate-mode:

> egui only repaints when there is interaction (e.g. mouse movement) or an animation, so if your app is idle, no CPU is wasted.

[amelius]

Iiuc, a tiny clock in the top right corner of the screen will trigger O(n) work where n is the number of elements on the entire screen. On every change of the clock, e.g. every second. This may be more if there are smooth animations, e.g. 25 times per second if that is the animation frame rate.

[Aeolun]

Sure, but it will consume less CPU than an idle instance of Electron. Or the effort it takes to redraw a React app even once.

[ModernMech]

There are two modes, reactive and continuous. You can switch between them here in the backend tab:

https://www.egui.rs/

Reactive mode is the one you are looking for.