I converted a somewhat large vi from LV 2012 to 2016. Now when I edit the app in 2016 the update takes 1 to 2 minutes or more before it completes churning on doing the update. Is there a method to look under the hood to see why LV 2016 is having trouble editing the converted app?
I assume that by "edit" you mean any change on the block diagram or front panel. Can you post the single VI? So we can try and help ruling out your installation / environment.
Get the latest LabVIEW 2016 patch (f6). It looks like the f5 patch should fix the issues you are seeing, but you might as well get the latest. More details: LabVIEW 2016 Patch Details (download links at the bottom of that page).