Having placeholders is part of what I’m talking about when I say lag, and jank is about dropping frames so that things do not appear smoothly animated. Not everyone is as sensitive to jank or they’re ok with it, but if you use something that lacks jank in the animations it feels better even if you don’t know what jank is.

The media detection thing might be related to Infuse and not to Jellyfin itself, since it sounds like everyone else isn’t having this issue, which is good to know.