"not having a JIT" is not a problem, it's you speculating that a JIT will improve performance, the real problem is "GDScript has poor performance", which in this context (me saying C# in godot sucks) is you speculating that C#'s performance is better than GDScripts. Do you have any data to back that claim up? Like real world data from a real product? Or are you just speculating with vibes?

If performance is a concern, skip C# and go straight to c++. Now your ripping at max speed with the smallest binary! That's my whole point. GDScript + c++ is my point. Ditch C# it's not worth the squeeze.

Some people like nice tooling with performance.

Interpreter code is never faster than a dynamic compiler, otherwise what about doing games in Python?

As mentioned on my comment, GDextension experience kind of sucks.