Fixing webapp speed is really hard job, mostly because it’s hard to find a bottleneck. And I want to show some tools that Google Appengine gives you for this job. Actually i’m going to tell about combination of two tools, that works just perfectly together.
First thing is Traces (under Monitoring tab in Cloud Console). It’s kind of a new tool, and I didn’t pay much attention earlier, just played a little. I thought it’s just another view to your logs, from Appengine APIs point of view:
It shows you details about requests, with information about which API calls were made, how much time server spent on them, how much it did cost, etc. Pretty useful information btw.