Switching to a cached version of Stack.empty, saving 16 bytes per Actor. Switching to purging the Promises in the ActorRefProvider after successful creation to conserve memory. Stopping to clone the props everytime to set the application default dispatcher, and doing a conditional in ActorCell instead.

akka-remote/src/main/scala/akka/remote/RemoteConnectionManager.scala

@@ -52,6 +52,8 @@ class RemoteConnectionManager(
 
   def size: Int = connections.connections.size
 
+  def isEmpty: Boolean = connections.connections.isEmpty
+
   def shutdown() {
     state.get.iterable foreach (_.stop()) // shut down all remote connections
   }