This change stops sleekxmpp from spending huge amounts of time unnecessarily computing logging data that may never be used. This is a HUGE performance improvement; in some of my test runs, unnecessary string creation was accounting for > 60% of all CPU time.

Note that using % in a string will _always_ perform the sting substitutions, because the strings are constructed before the function is called. So log.debug('%s' % expensiveoperation()) will take about the same CPU time whether or not the logging level is DEBUG or INFO. if you use , no substitutions are performed unless the string is actually logged

examples/ping.py

@@ -72,7 +72,7 @@ class PingTest(sleekxmpp.ClientXMPP):
             self.disconnect()
             sys.exit(1)
         else:
-            logging.info("Success! RTT: %s" % str(result))
+            logging.info("Success! RTT: %s" , str(result))
             self.disconnect()