This is exactly something I've been looking for to experiment with user segmentation, but crucially for fast, ad-hoc segmentation. Seems to bear some similarity to what Facebook [1] does for its audience insights.
SlicingDice founder here. We built SlicingDice exactly for this kind of necessity, very fast user segmentation. Actually, we just developed it because we didn't find any other solution that could support our needs.
User segmentation was actually the original use case that prompted Pilosa's development! Segmenting hundreds of millions of users with tens of millions of potential attributes.
[1] https://code.facebook.com/posts/382299771946304/audience-ins...