mxcl/homebrew — pull request #19870 by tt (2013-05-16 18:23:15+00:00)
Title: Improve performance of `brew leaves` command

I thought the `brew leaves` command was pretty slow, so I optimized it.

The current version will resolve a dependency graph of all formulae, where my change will only consider the installed formulae. On my machine, this yields a great performance improvement:

% time brew leaves
[...]
brew leaves 1.43s user 0.26s system 96% cpu 1.755 total

% time brew leaves
[...]
brew leaves 0.13s user 0.05s system 96% cpu 0.189 total

I have both known and "unknown" stuff installed, and the output before my change is exactly the same as the output after my change.