Question Best way to compare 2 bodies using ARKit

I'm trying to create an app which compares how similar 2 human bodies are.

On 1 side of the screen is the user's body being tracked with ARKit live, forming a 2D skeleton on run-time. And on the other side is a pre-recorded video of another user which already has a 2D skeleton.

The current solution that I thought of is saving the position of each joints to a text file every few frames for the user that is doing the recording of themselves. Then use that to compare each joints to the user doing the tracking live.

But I think this method is kind of slow and inefficient.

Does anyone know a better solution to this?