When you set a
GameObject as static, Unity starts optimising behind the scenes and assuming stuff about your objects. If for example you mark multiple objects as "batching static" you are basically telling Unity that these objects will never move. This means there is a chance on your final game all these objects will be "merged together" as one mesh, and be rendered like that, to make performance faster.
This is just one example, as far as I know the optimisation behaviour in Unity is not defined, and can be different from platform to platform as different things can be faster or slower on specific devices.
Although I can't know in detail, I image that when you are disabling/enabling static objects in a scene, you interfere with these optimisations, as it's not possible to disable part of a mesh.
A simple rule is, if your
GameObject is not really static and needs to be moved or be altered in any other way, do not mark it as static. Make sure you are not trying to prematurely optimise your project, make something that works, and when that's done, only then start optimising on the most performance-intensive parts.