Terrible docker performace

Hi I am just having a play with docker and tried to change from nginx compiled with rmtp on debian8 to running a docker container with nginx and rmtp. The problem I am having is the non-dockerised nginx runs video stream fine, but the dockerised version runs for maybe 2 secs and then freezes for 5+ then runs for 2secs again, then freezes etc etc.

Load via top is negligable…

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root@debian8:~# docker version
Client:
Version: 17.03.0-ce
API version: 1.26
Go version: go1.7.5
Git commit: 60ccb22
Built: Thu Feb 23 10:53:29 2017
OS/Arch: linux/amd64

Server:
Version: 17.03.0-ce
API version: 1.26 (minimum version 1.12)
Go version: go1.7.5
Git commit: 60ccb22
Built: Thu Feb 23 10:53:29 2017
OS/Arch: linux/amd64
Experimental: false
root@debian8:~#

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root@debian8:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ea62380470da tiangolo/nginx-rtmp “nginx -g 'daemon …” 2 days ago Exited (0) 7 minutes ago nginx-rtmp

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root@debian8:~# uname -a
Linux debian8 3.16.0-4-amd64 #1 SMP Debian 3.16.39-1+deb8u2 (2017-03-07) x86_64 GNU/Linux
root@debian8:~#