Did most of the optimisations that recent profiling suggested.
This sped up a git annex find
from 3.53 seconds to 1.73 seconds.
And, git annex find --not --in remote
from 12.41 seconds to 5.24 seconds.
One of the optimisations sped up git-annex branch querying by up to 50%,
which should also speed up use of some preferred content expressions.
All in all, a very nice little optimisation pass.