We've been getting reports of poor performance for our Gmail contextual gadget from our users between approximately 13:30 and 17:30 UTC every weekday.
This has been occurring since late November.
We've been able to observe the issue ourselves and can see via browser dev tools that the gadget code itself downloads direct from our CDN very quickly.
However subsequent requests from the gadget to our application which are proxied via Google's servers (*.a-gm-opensocial.googleusercontent.com) are intermittently taking much longer than expected.
These requests usually take less than a second. But during the affected period they're taking multiple seconds to complete (typically 5 to 15 seconds but also upwards of 30). We also see intermittent 502s returned.
We've raised the issue with Google.
Is anyone else experiencing a similar problem?