Appstats is a “library for App Engine that enables you to profile your App Engine app’s performance, and see exactly what API calls your app’s making for a given request, and how long they take. With ability to get a quick overview of performance of an entire page request, and to drill down to details of an individual RPC call, it’s now easy to detect and eliminate redundancies and inefficiencies in the way your App Engine app works. Appstats is available for both the Python and Java runtimes. Enabling Appstats is remarkably straightforward. In Python, it can be made to work with any Python webapp framework. For the full lowdown, see the docs, but here’s the quickstart if you’re using a supported framework,” explain Google.
Full Article: Easy Performance Profiling with Appstats