Performance hit as server?
Does the server take a performance hit when displaying as a vnc server?
Been using vnc for a long time and have always wanted to figure this out.
One of the reasons Redstone Software chose VNC was because of it's intelligent design which allows the protocol to adjust based on available CPU resources. VNC does use some processing to compress and send screens to the VNC clients, generally however it is a very small performance hit.
Sometimes people will look at the "% of CPU usage" and see that VNC is up at 100% and be concerned, all this means is that all the other processes on the machine are idle and the only process doing anything is VNC, which uses spare cycles to keep the remote screen up to date.
For people who are particularly interested in having VNC impact the machine in the smallest way possible we recommend choosing the encoding that is right for you. The smaller encodings (ZRLE, ZLIBHextile) will have the least impact on network bandwith but will cause both the client and server to work a little extra. If bandwidth is not an issue (running on a LAN) then feel free to use Zlib(Raw), Hextile or even uncompressed RAW) which will impact the CPU the least. Also - be sure to have only one connection to the VNC server at a time for the least impact.
Finally as one last note - if you are tesing a long running process (more than 1 minute) and really want to remove the impact, go ahead and disconnect from the server for a while and reconnect a bit later. When no clients are connected the VNC server has extremely minimal impact to the machine it's serving.
Thanks so much for that comprehensive answer!