Q: Slow VNC to Mac

There are a whole bunch of questions about very slow performance of VNC when using it to login to a Mac. Among them:

VNC Access Slow

VNC connection to an iMac running Lion from Windows - very slow

Extremely slow Remote Desktop via VNC

VNC From Windows to OS X Screen Sharing is Slow

I had the problem also. I've gotten around it, as described below.

First, my situation:

• Near computer (the one I'm sitting at): iMac 20". Native screen res: 1680 x 1050. (2007 vintage) Running 10.11.1 El Capitan
• Far computer (the one I'm trying to see by VNC): Mac Pro with 24-inch Cinema display. Native screen res: 1920 x 1200 (early 2009) Running 10.11.1 El Capitan
• Connection: VPN from home to work over Junos Pulse Secure. Ping shows an average round-trip time of 24 ms.
• Using: Native VNC built into OS X: Finder: Go: Connect to Server... vnc://[remoteMacAddress]. Running in "Full Screen" mode with "Adaptive Quality".

With the native setup, I figure I was getting about 1 sec from clicking on something to seeing the change on my screen.

My workaround:

1. On the far computer, open System Preferences / Displays. Change Resolution from "Default for display" to "Scaled". In the list below, select: 1600 x 1000. This change alone got me most of the improvement I see.
2. In the "Screen Sharing" menu on the near computer, under "View, uncheck "Turn Scaling On". This may have gotten me a bit more performance, but it's hard to tell.

Note: I think the key is, in step 1, to select a resolution that is Smaller than the native resolution of the near computer's display. Turning Scaling off just simplifies the situation a bit more.

Hope this helps.