var factory = MessagingFactory.CreateFromConnectionString("blah");
sender = factory.CreateMessageSender("MyTopicName");

var tasks = new List<Task>();
for (int i = 0; i < 10; i++)
    tasks.Add(sender.SendAsync(new BrokeredMessage("My Message")));

await Task.WhenAll(tasks);  // This completes within a few millis

receiver = factory.CreateSubscriptionClient("MyTopicName", "MySubscription");
_sbClient.OnMessageAsync(async message =>
{
    var msg = message.GetBody<string>();
    // log time-taken: 200+ms gap between log statements
    await message.CompleteAsync();
});