Prime require cache with atom exports

src/atom.coffee

@@ -60,6 +60,10 @@ window.atom =
     _.values(@activePackages)
 
   loadPackages: ->
+    # Ensure atom exports is already in the require cache so the load time
+    # of the first package isn't impacted by being the first to require atom
+    require '../exports/atom'
+
     @loadPackage(name) for name in @getAvailablePackageNames() when not @isPackageDisabled(name)
     @watchThemes()