This demo shows one of the fastest ways to send the image from one PictureBox to another PictureBox via the Winsock control.
The demo Project is both a client and a server. You can test it by running one copy and leaving "Server" set to localhost. You can also run a second copy on another machine for testing over your LAN or the Internet.
As always, Internet testing may require that you set up port mapping on your NAT router. Port 1001 is hard-coded but easily changed.
On most machines the timing mechanism used here won't have adequate precision to be useful for local transfers since the transfer is almost instantaneous.