jashkenas/underscore — pull request #1649 by megawac (2014-05-24 15:02:15+00:00)
Title: Optimize _.pick and _.omit

Migrate the trivial optimizations from rejected pr #1639

The invert change is debatable, its about ~25% faster in ff and ~20% slower in chrome to the current method. I think it looks nicer than the string map :)

JSPerf of the changeset vs current master: http://jsperf.com/underscore-1639/5