Comment 5 for bug 1668950

I can verify that after upgrading to 1:0.9.12.3+16.04.20171116-0ubuntu1, that gsetting controls low graphics mode.

I had low graphics mode enabled before upgrading, using
~$ cat .config/upstart/lowgfx.conf
start on starting unity7
pre-start script
    initctl set-env -g UNITY_LOW_GFX_MODE=1
end script

which was how it was suggested to enable it at some point in the past. This script is still there after upgrade, but it seems people that have the script need to still set the new gsettings key to get the full benefit. (I'm not sure there's a better way, fwiw; I don't think this should block things, but I do think it's a little bit untidy).