C2 will always save the image/assets in reserve even if you remove all instances of the image.
Very true, but just imagine it with enemies, using pathfinding and line of sight. Or defense turrets somewhere or just objects with lots of conditional collisions.
Optional you can ofc enable/disable certain behaviours at runtime.
But recently I was a bit surprised; I forgot which topic, but, the OP eventually mentioned applying a trick to decrease memory load before closing the app, he simply loaded an empty layout first which made a huge quick memory-usage-reduction.
So, the more you have on your layout, (even more so with objects doing behaviours) the more your cpu runs to handle it all, and imo, reducing memory access speed / throughput.
This type of approach could greatly increased performance on larger layouts.