No, not really. It's not about the 3D capabilities (I have different types of issues there) or about GDScript per se (other scripting languages have even worse issues like the GIL in Python), but the issue I had is that a lot of time was spent doing these:
- Counting references.
- Variant related conversions.
- Resolving methods.
- Interpreting the bytecode.
- Sorting nodes before calling update functions.
- Triggering callbacks etc.
All of these would amount to a good percentage of the time spent in the main thread.
I managed to optimize by a combination of parallelism (gladly GDScript has no GIL!) and by rewriting somethings in C++.
I still have some bottlenecks with the rendering but that should be easier to scale back.
This is likely more an indictment of Godot's 3D capabilities or GDScript than scripting languages as a whole.