[3.0.19] Does Plex store metadata locally?

Every now and then, when the app is launched, it will take a few moments to load movie metadata, as if it were fetching it from the sever (WD EX4 NAS - Plex Media Server 09166-1993). I was wondering if Plex stored this metadata locally so that it would load instantly every time.

Also, when loading my movie collection, as it fetches the metadata it would often display connection lost, and reconnect after a few seconds taking me back to home. Not sure if this is a Plex issue or the NAS isnt powerful enough.

Maybe the NAS is not answering quickly enough? I believe the timeout for local connections is 5 seconds.