Start up slowness on 17.06.0-ce

[dailyherold]

Greetings,

We have a CD pipeline that uses dynamic build slaves. We recently updated our Docker version to 17.06.0-ce, and noticed that the first run start up s3mock:latest takes much longer (~8--15s) than any subsequent starts (~2s). The start up time continues to be quick, even after I stop, remove, and docker system prune -a all containers. s3mock logs don't show anything noteworthy.

Obviously start up times differ based on what's running docker, but I just wanted to see if you or anyone else noticed similar behavior. The delta between our new slaves, and old ones, really is minimal, and the docker version bump the main difference. Previous slaves didn't exhibit the same behavior. I don't think it's something wrong with this image, but just opening the issue in case others have observed the same so that we can discuss.

Thanks!

Slave details:

$ /etc/release/os-release
CentOS Linux release 7.3.1611 (Core) 
NAME="CentOS Linux"
VERSION="7 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="7"
PRETTY_NAME="CentOS Linux 7 (Core)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:centos:centos:7"
HOME_URL="https://www.centos.org/"
BUG_REPORT_URL="https://bugs.centos.org/"

$ uname -r
3.10.0-514.26.2.el7.x86_64

$ docker --version
Docker version 17.06.0-ce, build 02c1d87```