Can we save huge amounts of directory bandwith with Z_NO_FLUSH?
It seems our default argument when compressing with zlib is Z_SYNC_FLUSH. That's not ideal, though: in theory we would get better compression by using Z_NO_FLUSH. But, how much better? And would that work with our code, or would we need other changes?
We should at least investigate this in 0.2.5, though if the fix is nontrivial, it can wait for 0.2.6.