Slowdown when removing display


Hi there!

I’m working on a video-to-LEDs ofApp (it maps the pixels of a video to addressable LED strips) which I’m using for an installation opening next saturday

Everything’s fine… until I turn off the screen.
Then, everything slows down (like by a factor of 3 or 4) and I get this error:
ofAppGLFWWindow: 65544: Cocoa: Failed to find service port for display

If I create a VNC connection to this computer (even with the screen still off), everything goes back to normal.

Is there any option somewhere to cater with this ? (other than leaving a screen on for 3 months, which I’ll eventually do if I don’t manage to find a solution).

Any help appreciated.
Thanks in advance


Hi bltzr
I had a similar thing once with an openni application. VNC was all fine but without any attached screen i had a significant framedrop. i can’t remember why i thought its openni related though. apparently I finally just plugged in an old screen without even connect it to power. feels like voodoo but did the trick. speaking of voodoo, i was on a mac mini. maybe this is of some importance as aaron_meyers had also a similar isssue on mac mini.
here are the forum links from back then:


have you tried to disable vertical sync and instead enable a fixed framerate?



thanks @arturo that did it !

thanks also @michif



and, yes @michif that was on a MacMini (late 2014)


The Mac Mini’s disable their GPUs when there’s no monitor plugged in.

This is also a nice solution for this issue.


OK, thanks for the info and the link @ayruos !


fine! this finally explains the voodoo with the plugged in but powerd off screen…