I’ve been looking more into the Godot GUI lags on tree change issue with the help of a friend in Godot 4.2.2. and we’ve managed to track down the root cause to the RichTextLabel
taking a long time when it is first drawn.
RichTextLabel
uses another class to draw text called TextParagraph
. Consider the example below, where TextParagraph
is used directly:
Normally, the draw performance is fine. However, also consider that we want to render the following text (like I want to do in no signal):
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Under these conditions, the first draw call takes about 100ms on my machine to run (and about 300ms) on my laptop. However, subsequent draw calls take only 1ms. It seems like TextParagraph
is lazily loading in some data when the first draw call happens.
We can proactively trigger whatever it is that TextParagraph
would otherwise do before the first draw call…
…and this fixes the lag that happens on the first draw call.
So, it looks like the performance problem isn’t an issue with tree changes, but rather something that the RichTextLabel
does when rendered for the first time.