+// Delay in milliseconds before updating.
+// We will adjust this during editing to take into account the actual
+// average round trip time measured during update_preview_now.
+var delay = 1000;
+
+// This is used to measure the average round trip time.
+var rtt_sum = 0;
+var rtt_n = 0;
+var rtt = 0; // Actual average RTT measured (ms).