Temporary views were indeed abandoned in CouchDB 2.0. With mango, you could emulate them using a Hack, but that's just as bad (read: performance-wise). The recommendation is to actually use persistent views. As only the delta of new or updated documents need indexing, this will likely need significantly less resources.
As opposed to relational DBs, the created view (which is a persisted index by keys), is meant to be queried many times with different parameters (there is no such a thing as a query optimizer taking your temp view definition or something). So, when you're built heavily on temporary views, you might consider changing the way you query in the first place. One place to start is thinking about which attribute will collapse the result set most quickly to what you're looking for and build a view for that. Then, go query this view with keys and post-filter for the rest.
The closest thing you can do to a temporary view (when you really, really need it) is creating a design doc (e.g. _design/temp<uuid>
) and use it for the one query execution.
Just to add a link (not new - but timeless) on the details: http://guide.couchdb.org/draft/views.html