Difference between TightVNC 1.3 and latest TightVNC 2.x viewer rendering

[Sudhir N. <sud...@gm...>]

Hi,
   I had compared the performance of TightVNC 1.3 viewer and TightVNC 2.x
viewer to same device with TightVNC 2.x server on a windows 10 device. I
see a big difference in speed of rendering the updates with latest TightVNC
2.x.

I appreciate TightVNC design and development team for this drastic
difference in rendering the updates. However I would like to understand
what is the major difference factor in design which made this huge
improvement. I had observed that the SetPixelV() API is consuming most of
the time while rendering for old TighVNC 1.3 viewer. However I haven't
explored much of the latest TightVNC code yet and wanted to explore it in
future. I would like to know few pointers in the design and code which is
making the major difference in the  speed of rendering in latest TightVNC
2.x if someone can help me.

Appreciate your response in advance.

Thanks
Sudhir