diff --git a/Gemfile b/Gemfile
index 59c357c..f04a59b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -19,3 +19,5 @@ gem 'jquery-rails'
 gem 'ejs'
 
 gem 'simplecov'
+#gem 'perftools.rb'
+
diff --git a/lib/jasmine/headless/files_list.rb b/lib/jasmine/headless/files_list.rb
index 7887713..7456559 100644
--- a/lib/jasmine/headless/files_list.rb
+++ b/lib/jasmine/headless/files_list.rb
@@ -203,7 +203,7 @@ module Jasmine::Headless
     end
 
     def expanded_dir(path)
-      Dir[path].collect { |file| File.expand_path(file) }.find_all { |path| File.file?(path) && path[extension_filter] }
+      Dir[path].find_all { |file| file[extension_filter] }.collect { |file| File.expand_path(file) }.find_all { |path| File.file?(path) }
     end
 
     def extension_filter
@@ -221,11 +221,11 @@ module Jasmine::Headless
     end
 
     def src_dir
-      config_dir_or_pwd('src_dir')
+      @src_dir ||= config_dir_or_pwd('src_dir')
     end
 
     def spec_dir
-      config_dir_or_pwd('spec_dir')
+      @spec_dir ||= config_dir_or_pwd('spec_dir')
     end
 
     def spec_file_searches
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 54f9d56..17ad330 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -3,6 +3,11 @@ if ENV['COVERAGE']
   SimpleCov.start
 end
 
+if ENV['PROFILE']
+  require 'perftools'
+  PerfTools::CpuProfiler.start("/tmp/jhw-profile")
+end
+
 require 'jasmine-headless-webkit'
 require 'fakefs/spec_helpers'