alt Hacker NewsToyota complained about poor performance on all of Unity, UE and Godot, but also about long startup times with Godot.
I don't know how bloated Godot is, but AFAIK libgodot development started as part of Migeran's automotive AR HUD prototype so I'm surprised to hear it has poor startup time for a car.
Godot is pretty lightweight (especially considering how powerful it is), generally about a second or less. But maybe they are looking for a fast enough startup time that the engine can be started when showing something onscreen and torn down when not visible. In which case, I can see the startup time being an issue.