There were a lot of complaints from people that had infrequently used (new) web apps, and so there would be a substantial delay to spin up an instance when the app did get hit. This makes your site seem "slow" even though it really isn't, which is a big problem if you are trying to build some momentum, or show off your site to potential investors. People were resorting to some less than ideal ways for keeping their instances warm, more information on the app engine for java group: http://code.google.com/p/googleappengine/issues/detail?id=24...