Self reply to mention that one reason it feels so "instant" is that in many cases, it has already auto-completed and started displaying your destination before you finish typing. For instance, I typed "golden gate bridge", and probably by the time I had typed "golden ga" it could start loading, and everything was loaded by the time I finished typing "bridge."

Also, what panoramic viewer is this? Is this something provided by Google, something off the shelf, or something custom written by them?