I'm trying to animate a bullet charging for my enemies.
I'm animating the radius and height of 2 MeshInstance that both have materials on them. One is transparent and the other one is opaque.
I'm using Godot 3.5.3 and the FPS drops as soon as the animation start playing.

Do I need to upgrade to godot 4.2 for better performance on this matter or am I doing something wrong ?

The animation :

The Meshs :

no. what you are trying to do, you are doing it wrong. you will always get bad performance editing a mesh, in godot, in unity, in unreal.
since you are trying to change radius and height, a better way would be use a vertex shader or change the mesh/Node3D SCALE, since these are communicated to the gpu as single uniforms, while editing the mesh by changing radius forces the mesh to be remade and sent to the gpu as vertices.