Hi @kroofy
Sorry for the late reply. Just so you know, support is handled through emails via the support ticket submission here: http://support.advancedcustomfields.com/new-ticket/
This forum is for general discussion between users.
As for the issue, I’m glad to hear there is a increase in performance in 5.1.8.
The piece of code you have highlighted is run when a sub field is being triggered by conditional logic. I agree that this is most likely a bottle neck for performance, but I am unsure as to how I can optimize it for many fields. Are you able to add in a console log within that snippet to see how many times it is run, and what data is found? Perhaps you could event console log some times to find out the speed issue?
Thanks
E
