Is there an option to load objects/scenes I want to memory to prevent lags? I don't want to let all objects spawn to buffer them or other tricks. How can I do this? And is it possible to remove them from memory? Thanks for every answer!
You want to prevent lag when changing scenes? Add them all in the first frame (so you get a massive lag spike), and have each scene pause itself. Then you can resume them as needed.
To remove it from memory, end the scene.
I don't feel that I actually understand what problem you are having.
To load objects and scene into memory you need LibLoad
from bge import logic logic.LibLoad('file.blend','scene', load_actions = False, load_scripts = True, async = False)