Scene with many nodes and 512px script icon causes bad lag spikes

[nathanfranke]

Godot version:
cdbf0332902d34cfb3be7899fb738b5447bbb755

OS/device including version:
Linux Mint 19.3

Issue description:
Multiple instances of a node that has a high resolution script icon causes bad lag spikes.

https://www.youtube.com/watch?v=tnT5knlqbqI

Steps to reproduce:
Move any nodes in Scene.tscn and it will have a 1-2 second lag spike.

Minimal reproduction project:
Lag.zip

[Calinou]

Note that you generally don't need node icons to be larger than 32×32 (if you want to support hiDPI displays) or 16×16 (if you don't want to support hiDPI displays).

We could display a warning message if a node icon larger than 32×32 is loaded by a script (either using the custom type system or class_name). Likewise, we could also display a warning message for icons smaller than 16×16 (just in case).

[nathanfranke]

@Calinou that's true, so this isn't the highest priority. Although the bug seems to be more prominent when there are more instances which could cause noticeable delay even with 64px (+ many instances)

Edit: I actually disagree with the warning message idea. While icons shouldn't be larger than 64px, there is still a fatal design flaw that is causing the lag and that should be fixed no matter what.

[YuriSizov]

This should be fixed in master by #75472.