  Due to the widespread adoption of "work-from-home" policies,
videoconferencing applications (e.g., Zoom) have become indispensable for
remote communication. However, these systems lack immersiveness, leading to the
so-called "Zoom fatigue" and degrading communication efficiency. The recent
debut of Apple Vision Pro, a mixed reality headset that supports "spatial
persona", aims to offer an immersive telepresence experience with these
applications. In this paper, we conduct a first-of-its-kind in-depth and
empirical study to analyze the performance of immersive telepresence with four
applications, Apple FaceTime, Cisco Webex, Microsoft Teams, and Zoom, on Vision
Pro. We find that only FaceTime provides a truly immersive experience with
spatial personas, whereas other applications still operate 2D personas. Our
measurement results reveal that (1) FaceTime delivers semantic information to
optimize bandwidth consumption, which is even lower than that of 2D persona for
other applications, and (2) it employs visibility-aware optimizations to reduce
rendering overhead. However, the scalability of FaceTime remains limited, with
a simple server allocation strategy that potentially leads to high network
delay among users.
