Performance problems with zfs storage driver

We’re seeing horrible performance using zfs as a storage driver. It can take minutes to build trivial images that used to build in tens of seconds with the other storage drivers. Frustratingly, the docker developers have stopped responding to my issue on github ( Can other folks who are using zfs try the sample images in the issue? I’d be interested in seeing the debug logs for someone who gets reasonable performance to see what might be different.