Hiho, I recently rooted my TV and installed this app.

I can enable "show previews with sound", when enabled, it takes 3-4 seconds (which is pretty long, but I don't know how long it took on the official app. I never used it) for the preview to show, but I don't like it with sounds on, so I disabled it. Previews on the official app are pretty much instantaneous.
But here are no previews at all. That's a bummer.

Also, when I scroll to all my subscriptions it takes pretty long 😅 on the official app it's smoother/faster.
Some other transitions are also smoother on the official app, it's hard to describe. But that's not a big issue.