documentcloud/backbone — pull request #1364 by TheCloudlessSky (2012-05-31 18:47:28+00:00)
Title: Improve performance of Collection#contains

Rather than using `_.contains()` which is O(n), I've removed the underscore proxy and increased the performance of `contains()\include()` to O(1). I assumed checking by `cid` would be best in case an `id` isn't set.