I've noticed a huge decrease in performance after installing 2018. I know there where changes on the backend and so far my VAR has basically told me that as long there's no errors it's working "correctly"... They did acknowledge the performance stinks and was being addressed by SW.
You'll have to check with your reseller, I don't have a list of the required ports.
I'm not familiar with ESET Endpoint works, but you may want to try leaving the firewall turned on and adding a few rules to the anti-virus to not scan the PCB Vault files. I found that improved performance some with Sophos Endpoint as it was constantly scanning all of the changes to the vault files as I was using PCB.
We will do some tests turning off AntiVirus as you recommended. It's definitively related to AntiVirus/FireWall.