I am already using ccache to speed up recompilation when building Bitcoin Core PRs. Are there any other ways of speeding up the process?
Will Clark answered this question on IRC.
You can reduce the time it takes to run
./configure by using
./configure -q -C.
-q is quiet and
-C removes terminal printing and uses a cache (like ccache). It reduced Will's configure time from 29 seconds to 10 seconds. For more details see this info page.