Hello,
First image is an empty level without post processing volume, second image is the same level with a post processing volume dragged into the level.
Why is it costing 24 frames while I have touched nothing?
You haven’t lost 24 frames, you have lost 0.18ms, or 1% of the duration of a 60fps frame. You are just measuring the baseline cost of the post-processing subsystem - the cost to run the code without any processing attached. 0.18ms is tiny.
Also, you can’t really benchmark it that way, you would need to test in an actual scene