Question: I'm using gae for a project and I have a cron script to keep it alive so that the handful of users I have so far wont have to wait +5 sec on their first query.

Does anyone know if Google will enforce some limit on my app if the logs reflect that there are significantly more hits from the cron script than actuall users?

Thanks

Answer: 
To address the wait time that you are facing, App Engine has a feature called Warmup requests. Warmup requests are a specific type of loading request and their task is to load the application initialisation code into an instance in advance before the standard requests from your users hit the application.

Please look at [Warmup Requests](https://developers.google.com/appengine/docs/java/config/appconfig?csw=1#Java_appengine_web_xml_Warmup_requests) documentation and a [tutorial](http://googcloudlabs.appspot.com/codelabexercise9.html).
so far google has no such criteria but better option is enable billing with automatic scaling 
it really helped me to pace my site's speed.

if you are really worried on pace increase min idle instance and decrease pending latencies you can find them on your dashboard if your app has billing enabled.