Top comment leaves out HDCP entirely as well which I would wager is where a lot of people experience delay. If you want to learn more about it search for the

Top comment leaves out HDCP entirely as well which I would wager is where a lot of people experience delay. If you want to learn more about it search for the edid hotplug detection. Once that gets negotiated it is followed by the hdcp handshake. Keep in mind while reading up on this the industry terms for devices are "source" and "sync". Video goes from source to sync. The hdcp handshake is a particularly bad mess which most manufacturers don't implement well due to a very confusing spec. My experience has been some devices start showing video right away and kill it if hdcp handshake fails, while other devices don't show video until hdcp handshake succeeds. Behavior is quite hardware dependent. The commercial vendors like Extron (crosspoint switchers) and Crestron (digitalmedia switchers) have this figured out pretty well where switching is almost instant so it's definitely possible. I think Crestron has some technical papers out there that discuss the challenges involved.