So I did some rough time measurements using a typical mount and flight.

With Palace of the Dead, it wasn't even worth mounting up, as you'd get there in 2 seconds max from the aetheryte.

With Heaven on High, it was roughly 5 seconds from the aetheryte to the NPC.

With Eureka Orthos, it was 52 seconds from the Mor Dhona aetheryte to where the NPC would be stood, and that includes the loading screen for the Crystal Gate on an SSD. Not to mention that if the area's instanced, that's going to cause serious problems on launch, as many of us know all too well.