Nail on the head for me. Disabled appnap globally (s3D is not appnap aware) and problem instantly gone. Thanks.alien2108 wrote: ↑Sun May 25, 2014 7:13 amAre you on OS X by any chance?
You have to be EXTRA careful then, since OS X 10.9 has App Nap feature and if Simplify3D (or Pronterface....) is not in foreground, Application will pause!!! You can disable App Nap if you open Application properties and select "Prevent App Nap"!