DFMirage Driver

It's a recommended add-on if you use TightVNC with Windows 7 or earlier version.
It's not needed with Windows 8 and above.

DFMirage mirror display driver allows TightVNC to gain the best performance under old versions of Windows.
With DFMirage, TightVNC Server can detect screen updates and grab pixel data in a very efficient way.
If you use TightVNC as free software, DFMirage is FREE for you as well.