Anecdotally, ~1000+ views can be performant in Backbone.
It's hard to say what bottlenecks you were hitting but zombie views that can't be GC'd, rendering to the page thousands of times (instead of to an in memory DOM element), or sorting your collections on dynamic, non-memoized values could have caused those kinds of slowdowns.
It's hard to say what bottlenecks you were hitting but zombie views that can't be GC'd, rendering to the page thousands of times (instead of to an in memory DOM element), or sorting your collections on dynamic, non-memoized values could have caused those kinds of slowdowns.