I have already a few months a new MacBook Pro, but I noticed that Java applications (read: webstart appliciations) where starting a lot slower than on my old macbook.
I thought it was maybe I had a wrong dongle or something, but that was not the case.
I found this solution on the internet, and it worked instantly.
https://www.igorkromin.net/index.php/20 ... os-sierra/
My java webstart solutions, are now started blazingly fast again!
Hope this helps someone else.