Comment 72 for bug 1690980

@Ethan Based on profiling real-life scenario (updating unstable with 100+ packages) I believe I was able to make u-u ~10 > times faster that should bring down the time of your test of upgrading xenial with all security updates to below one hour.
Since running only dpkg's part took more than 30 minutes I think this state is good for Artful and for backporting the fixes to older releases.
I've set up a separate PPA for u-u testing if you would like to verify the speedup & other fixes:
https://launchpad.net/~rbalint/+archive/ubuntu/unattended-upgrades