Some of the top reasons that your application/web site/mobile app is slow;
10) I thought you turned off the diagnostic logging
9) Do you really have to index a table with five years of history and one Billion rows
8) You doubled the number of calls from the application tier to the database tier for the same workload and were surprised by the increase, which no one noticed until production.
7) They moved the application server to another continent
6) They virtualized it (you weren’t using all the real CPU anyway)
5) You wrote your own caching component and didn’t really understand the impact of flushing the cache
4) Even Amazon Web Services stops allocating Servers (thought you could buy your way out)
3) The Marketing group ran a hugely successful ad on a major TV program and you under estimated the new workload. The good news is you and the CIO are on a first name basis.
2) They upgraded to a new version of the Application server/database server/etc. and no one thought a performance test might be needed.
1) The business critical Applications don’t have performance goals, how do you know its slow?
Also, I like “Is there really a difference between polling and event driven programming?”