Mac mini VPN headless, slow graphics performance when no monitor plugged in

I am using a Mac mini, headless, with no monitor, keyboard or mouse, via VPN from a Windows machine over a LAN. Everything works fine and setting everything up was a breeze. However, something very odd I noticed was that if my Mac mini does not have a monitor plugged in to its video output, the rendering of the graphics over the VPN is very slow. It is most noticable when hovering over the dock and activating the animations etc, though it is noticable all the time. It's so bad that it would be IMPOSSIBLE to watch a video clip or simple animation. It's as though frames are being dropped. Now, this can be immediately fixed if a monitor is plugged into the Mac mini and turned on, and the VPN to the Mac mini from my Windows machine works flawlessly and the graphics are rendered perfectly, with little to no delay or frame skipping.

I have a hunch that the Mac could be disabling some kind of graphics acceleration when the monitor is not plugged in, but I am not a Mac expert by far, this is my first Mac experience. It was purchased solely for the VPN and headless use, so if I can't get it working properly, it's a waste.

Note, I have tried several VPN client/viewer combinations and they do not change the situation.

Thanks in advance.

Message was edited by: HopkinFrog

Also, when I try to use the remote with the Mac mini (pressing the menu button), over VPN with no monitor attached to the machine, I simply get a white blank screen until I press the menu button again.