RR only reads tags for display in the playlist. It does NOT build a Database/Index of files or tags.
There's a plugin by BlueZX3 that uses a SQL database, but it's not a built-in feature.
The only "database" (alike) support built-in RR for browsing Artist/Genre/Album is based on Winamp's Library -- which you'd have to build outside RR (in Winamp's settings), that is, IF you want to use this feature -- and in this case RR won't read the tags at all, but will just load them up from the Winamp Library. The Winamp Library can be scanned manually (at request), at the start of winamp or at specified periods (all of which can be done in the background while winamp/RR run).