Async/Await and What It Actually Costs You in the Cloud
TL;DR for leaders: on the same 1 vCPU / 2GB container, an ASP.NET Core endpoint written with correct async/await sustained roughly 9 times the request rate of an identical endpoint that blocks on the same call (.GetAwaiter().GetResult() instead of await), before the bad version collapsed entirely under load. At 2,000 requests/second, that’s the difference between 1 container and 9, or roughly $12/month versus $112/month on Azure App Service for the compute alone, scaling worse the more traffic you add. The code difference between the good and bad versions is a single line. This is a measured result from a benchmark you can run yourself, not a vendor estimate; see “Caveats” below for what it does and doesn’t tell you about your own system. ...