Thanks, Danny, & Happygreenfrog.
Edit: Also, I've read more on the subject, so I've become a little more knowledgable about it.
This have been asked before by other users but no answer:
1) To make a background out of 12 unique active static objects 256x256px, each containing 1 frame is better performance wise than making 1 object with 12 frames and duplicate the object 12 times?
Worded differently, is it better to use duplicates containing many frames or use many unique objects with 1 frame?
2) Duplicate frames in an animations? Do they take up space in a spritesheet and therefor memory?
2) Background images lowers performace more than a static object? So as a rule thumb maybe not use them at all?
About "Power of 2"
If I have a lot of blocks that are 56x56 pixels, and they need to be that size in the game.
-Is it better to have the textures 56x56?
-Or is it better to make them 64x64 and them downscale them in Fusion for better performance?
Because my levels with many duplicates of the same object is making the game slow. Its a side scroller so it would be good if the objects were created just before they entered the scene, but that does not seem to be possible if I dont do it manually for each duplicate.