Return fast for built-in class icon

[YYF233333]

Add a fast path for built-in class in EditorNode::get_class_icon.

#78645 MRP with 28K objects now runs smoothly, 91K objects still sucks.

Would be good if someone knows what EditorNode::get_object_icon does could refactor these code.

Refactor get icon logic.

• Split _get_class_or_script_icon into _get_class_icon and _get_script_icon.
• Change get_class/object_icon to avoid multiple checking.
• Use file extension to identify resource path. This should be cheaper than ResourceLoader::exists.

Test with test_custom_icon.zip, class_name and @icon seems to work without problem. And the performance boost remains true.

Bugsquad edit:

• Fixes GDScript code completion is extremely laggy on Android Editor #98666.

[777joe]

Tried this out. This fixes #98666 too.

[Calinou]

Tested locally, it works as expected. It's faster overall but due to remaining bottlenecks, scrolling large Trees is still sluggish, especially when near the bottom.

Code looks good to me.

All tests done with an optimized editor build with theMRP from #78645.

I've also tried the MRP of this PR with 16,384 nodes (duplicated from the original 4 nodes) but couldn't spot much of a performance difference when scrolling.

Local

master

master_local.mp4

This PR

pr_local.mp4

Remote

Stutters due to Tree updates being performed every second are still present.

master

master_remote.mp4

This PR

pr_remote.mp4

[KoBeWi]

This looks mostly like a cleanup, while #101489 is a complete solution. The key point is avoiding to load scripts.

Still, it does not have problems I mentioned in #101489 (comment), and if it's indeed faster, then it's fine for now. The two PRs don't seem mutually exclusive.

[AThousandShips]

Code looks good

[YYF233333]

Unfortunately I cannot make this refactor after #101489, it will crash the editor when create node for unknown reason. But at least we can solve the performance problem first.

I also found a possible regression: after creating a new script and adding @icon, the icon doesn't load—it requires restarting the editor to appear. Don't know if it is related to #101489. I tested this on the dev version, not sure if the release version is affected as well.

Edit: This behaviour exists before #101489. (I kind of remember last month I do this test it doesn't require a scene reload but, anyway, not a big issue.)

[KoBeWi]

after creating a new script and adding @ICON, the icon doesn't load

It should refresh when you close and re-open the scene. Script icon cache is only invalidated when any scene is closed (though not sure if it's still the same after #101489).

[Repiteo]

Thanks!