At step #4 (page 3), I didn't perform any of the main entry that relates to 'snappy java', rather I opened the 'Oracle 8' entry and followed the 'Oracle 8' instructions
continue on with the installation as listed for the controller and you have Pi-hole with the Unifi controller all on the same pi
I didn't see any load impact with installing the controller with Pi-hole
Load: 0.01 0.05 0.01 (my example load report for a SOHO)
Is this really a good idé what happens if you need to put the DNS down for something?
Then your controller also goes down.
What I have done is that I have 3 stand alone Pi's one for DNS1 and one for DNS2 and the other for the controller.
But my network is big so....
And this is also because of the security as my Guest network can access DNS 1 and DNS 2 I don't want to put the controller on this machine as then they can also access the controller if I get a breach in DNS 1 or DNS 2 machines as they are on the same VLAN.