How much air?

[Fluffybuck]

....Note that doesn't mean springers are necessarily 3 times more efficient than PCPs though!....BB

But it does mean that for a spring gun the barrel length required to extract all the energy from the air pulse is much shorter.
A 12ftlb springer only requires about 10" barrel for .22 and 13" for .177. Rammers slightly shorter than that. PCPs about double that.

Many airguns have a barrel that isn't the optimum length for efficiency because other factors such as excessive overall length, excessive forend weight, cocking leverage or even cosmetics also influence the design.

[krisko]

Pcps are more efficient for me as I don’t have to use any muscle power. The tuxing compressor does it for me.
Air is readily available if you have your own compressor just like with a springer.