Bad performance on Azure for Owin/IIS application
This might not help you directly. but we had some performance issues after moving an application to cloud. Please find the discussion here:
Huge performance drop after moving to Azure
After a lot of investigation finally we found out our issue was with the Transient Fault Handling mechanism. It used to go and read the web.config each time causing huge CPU usage which was not an issue with same code in non-cloud environment. We handled it by using a Singleton pattern around it.
Hope it helps you to find out if there is any such issues with the application.
Cheers. :)
Since IIS 6 many requests are handled in kernel mode, which is generally faster than user mode.
It appears likely that in your case the static content is handled by the kernel mode cache, such that those requests don't involve user mode code. In most cases that's desirable due to better perf, etc.
more on content that can/cannot be handled by kernel mode
more on configuring/monitoring IIS output caching to verify its use in your test
Best of luck!