Godot 4
It's hard to find answers on this because it's an ignorant question. The question doesn't have an answer, because you're asking the wrong questions. Godot 4 doesn't have inherit performance issues. There are performance characteristics in the way that you approach a problem, just like with anything else. Inexperienced devs are always concerned about performance _before_ they dive into problem solving, but the answer is always to work through performance _after_ you solve the problem.