I'm testing on two monitors. The primary display has 1440p native resolution and has G-Sync. The Secondary display has 1080p native resolution and does not have G-Sync.
When testing in a window on the primary display the game runs fine. However if I switch to Full-screen enabled, stutter is introduced. There are no issues running in fullscreen on the secondary display.
Although this is a high spec system, I thought perhaps the difference between 1080p and 1440p may be causing the performance issue. I tried every scaling mode available in order to show less of the game on the larger display. The stutter happens even in 'letterboxing' and 'no scaling' modes.
I disabled G-Sync in the system wide settings under Nvidia Control Panel. Then ran another test build in full-screen. No stutter. Confirmed... Stencyl games are not compatible with G-Sync.
As an end user this isn't a big deal as you can just disable G-Sync. If you're someone looking to publish your game to desktop it's a bit concerning... I'm yet to publish a game but I can just picture the negative user reviews on Steam from butthurt G-Sync monitor owners saying the game's performance is terrible (unaware they can just disable G-sync to fix it). Therefore I've moved this to the issue tracker:
http://community.stencyl.com/index.php?issue=1752.0
