filefinder "cached" setting

(i have this set to `true` in ~/.atom/settings.coffee)

extensions/filefinder/filefinder.coffee

@@ -6,11 +6,22 @@ ModalSelector = require 'modal-selector'
 
 module.exports =
 class Filefinder extends Extension
+  settings:
+    cache: false
+
+  cached: null
+
   constructor: ->
     atom.on 'project:open', @startup
 
   startup: (@project) =>
-    @pane = new ModalSelector => _.reject @project.allURLs(), ({url}) ->
+    @pane = new ModalSelector @findURLs
+
+  findURLs: =>
+    return @cached if @settings.cache and @cached
+
+    # always set cached, whether if we care about it or not.
+    @cached = _.reject @project.allURLs(), ({url}) ->
       fs.isDirectory url
 
   toggle: ->