Nothing like saying it with numbers:  Timer periodic @ 1000ms, callback does some "heavy lifting" (read: while loop):

2014-05-07 09:29:07.867
done: 2014-05-07 09:29:08.956
2014-05-07 09:29:08.957
done: 2014-05-07 09:29:10.036
2014-05-07 09:29:10.037
done: 2014-05-07 09:29:11.114
2014-05-07 09:29:11.114