TeamViewer slow on Ubuntu without monitor 16.04

After restarting my server without a monitor connected, TeamViewer is extremely slow. But if I restart with a monitor it runs fine. How can I get it working like normal without a monitor attached?

Install a dummy server:

sudo apt-get install xserver-xorg-video-dummy-lts-xenial

Add a /etc/X11/xorg.conf file with the following contents:

Section "Device"
    Identifier  "Configured Video Device"
    Driver      "dummy"
EndSection
Section "Monitor"
    Identifier  "Configured Monitor"
    HorizSync 31.5-48.5
    VertRefresh 50-70
EndSection
Section "Screen"
    Identifier  "Default Screen"
    Monitor     "Configured Monitor"
    Device      "Configured Video Device"
    DefaultDepth 24
    SubSection "Display"
    Depth 24
    Modes "1024x800"
    EndSubSection
EndSection

Adding a fake monitor fixes the problem:

sudo apt install xserver-xorg-video-dummy
sudo wget -P /etc/X11 https://gist.githubusercontent.com/mangoliou/ba126832f2fb8f86cc5b956355346038/raw/b6ad063711226fdd6413189ad905943750d64fd8/xorg.conf