When should I mark GameObjects as Static?

Question

Here is the corresponding Unity documentation.

According to explanations of Unity documantation pages about Static GameObjects, sometimes marking GameObjects as static may effect performance in a bad way (for example Static Batching causes more memory usage).

So when should i exactly want to use these functionalities?

Thanks in advance.

Footnotes:
I'm currently developing a 2D top-down game which has lots of Sprites and LineRenderers, but no 3D objects (not even a quad). All GameObjects are being instantiated procedurally from premade prefabs. LineRenderers get updated from scripts each frame. And nearly all Sprites are moving constantly. Majority of Sprites share same material. All LineRenderers also share same material of their own.

Answer 1

There is no hard rule about when you should or should not make GameObjects static.

At the very least, only do it for objects that will never move in their lifetime. But you have to know what it does to evaluate whether or not you should.

It freezes the mesh into the scene data, so you don't have the overhead of the GameObject for the item. This means a performance boost at the cost of altering the scene data at build time and extra memory cost for the final built application.

This is fine in many cases, though it can cause problems, for example with forests. Also, it means that instead of storing the verts for the tree once and the GPU drawing copies, it has to duplicate those verts all over the place. That takes time during the build, and space in the app. Our app went from 3-4 GB to 300-400 MB when we made the trees not static. Build time went from 3-4 hours to 1 hour.

Having said all that! Your game is 2d, and would probably benefit from setting GameObjects in scenes to static, provided you don't have tons of them.

Answer 2

If I say in general then Everything which is gonna never move (not even a pixel) in whole app life should mark as static. Usually it is useful for baking lights, baking navmesh paths, so on..

Well, if you are developing with no 3D objects then just relax and get chilled. No need to worry about realtime rendering, shadows or any other issues. Even delete the only light comes with new scene ;)

Well, anybody can correct me if I'm wrong at any place.