The docs under general tips includes lazy loading, with each language providing a code example. Optimizations and best practices for Java and Python have their own dedicated page.
The Lazy-Loading sample could just be a Lazy<T> but ASP.NET has more options:
splitting controllers so heavy dependencies aren't always injected in the constructor
using [FromServices] and injecting into the action method
using minimal apis to define per-action dependencies
singleton for cacheable computation (possibly beyond the scope of the docs)
Need to consider which makes more sense. Potential topics to include
.NET 6 minimal APIs for performance
ReadyToRun & building for specific runtime (linux x64)
JsonFormatter in default aspnet6 container image and how that works with Cloud Logging
Ideally .NET 6 SDK is added to Cloud Shell. Alternatively, either provide instructions on how to extend the cloud shell image, or provide a Google-owned base image for the samples (less nice).