Use the `PROFILE=filename` env var to profile work.

Currently supported printer types are:
* `filename.html`: GraphHtmlPrinter
* `filename.txt`: GraphPrinter

For more printers see
https://github.com/ruby-prof/ruby-prof/blob/master/README.rdoc#printers.

Gemfile

@@ -44,6 +44,7 @@ group :debugging do
   gem 'kicker'
   gem 'awesome_print'
   gem 'pry'
+  gem 'ruby-prof'
 end
 
 group :ruby_1_8_7 do

Gemfile.lock

@@ -143,6 +143,7 @@ GEM
       powerpack (~> 0.0.6)
       rainbow (>= 1.99.1, < 3.0)
       ruby-progressbar (~> 1.4)
+    ruby-prof (0.13.0)
     ruby-progressbar (1.6.0)
     safe_yaml (1.0.4)
     slop (3.6.0)
@@ -178,5 +179,6 @@ DEPENDENCIES
   rake
   rb-fsevent
   rubocop
+  ruby-prof
   webmock
   xcodeproj!

bin/pod

@@ -30,4 +30,20 @@ end
 STDOUT.sync = true if ENV['CP_STDOUT_SYNC'] == 'TRUE'
 
 require 'cocoapods'
-Pod::Command.run(ARGV)
+
+if profile_filename = ENV['PROFILE']
+  require 'ruby-prof'
+  reporter = case (profile_extname = File.extname(profile_filename))
+  when '.txt'
+    RubyProf::GraphPrinter
+  when '.html'
+    RubyProf::GraphHtmlPrinter
+  else
+    raise "Unknown profiler format indicated by extension: #{profile_extname}"
+  end
+  File.open(profile_filename, 'w') do |io|
+    reporter.new(RubyProf.profile { Pod::Command.run(ARGV) }).print(io)
+  end
+else
+  Pod::Command.run(ARGV)
+end