It sounds like you are requesting a feature that simply would filter out artists not in your collection when working with similar artists ?
Svens suggestion is a quite complex one since it would require a total resign and load-on-demand logic (it's no prefered to load all data at once), but it is also the most powerful.
I think that grouping per-page with artists in the collection and not in the collection is perfered.
Rather low-prio at the momement since a lot of other is ongoing, but might be interesting for future releases.
Infusion
In Artist view (artist detail), when we click in "Similar", returns all artists, even the ones that are not present in our collection (with zero tracks). This makes more difficult to clearly choose what I can listen right now.
I think many things can be done about "similar", so here are some thoughts:
1. I would like to be able to see the Similar list before clicking into it (maybe just hovering the mouse (text list))
2. I think that would be nice that I could see the list divided: Artists in collection + Artists out of collection (this helps to search for new music)
3. When clicking in Similar, returning all artists, I would like see only artists present in my collection. I like to know other new artists, but in this view it doesn't help at all. Would use #2 instead.