Hi
As far as i know there is nothing like which ios code version consumes or reduces less cpu cycle with CRTP Compression.
Instead its the amount of traffic you are gonna generate and which is being compressed.
It also depends on the other feautres and process configured/used in the router which results in peaking the cpu to the max level.
Untill unless you dont have any known bugs with the ios code being used in your box i dont see any kinda CPU issues.
I would suggest to check out for a GD version of a ios code which can support CRTP and fit into your requirement.
regds