Hi We are running an Umbraco based web app in following setup at Azure: all content editing is done on VM with IIS, while Azure web app of S3 size is responsible for content delivery. App itself is pretty big (Umbraco.config is ~15 Mb, which counts to around 9000 nodes with a lot of Vorto content). Currently, when there near 400 active users (proven by Google Analytics and VSTS load test) we are observing following: HttpQueue length begin growing up, CPU load is also getting hire, which by it's own leads to web app performance issues. We have an autoscale rule, based on CPU metric to add 2 instances to the mix to cope with a load - but, this does not help, as new web apps does not have Examine indexes and caches are empty. So, it takes a considerable time to startup, and delivers awful user experience.

To fix this up, I will implement Azure CDN (to minimize amount of user request) with https://our.umbraco.org/projects/developer-tools/azure-cdn-toolkit-for-umbraco/

We also have a redis cache instance provisioned for session state storage. Maybe it is possible to transfer output cache there to allow faster web app startup on upscale event?

Is there any more suggestions or well-known practices to fix this problem?