Large delays in Windows Server 2016 containers

While running Windows service, written in C# using .NET Framework, in Docker’s container I observe large delays (several 100’s of msec) for 90% of requests, compared to the situation while running the service directly on the host.10% of requests are processed within the same time as if running directly on the host (~20msec). The service provides a REST API and communicates with MSSQL server and RabbitMQ.
Image is microsoft/windowsservercore, the latest. Installation type is Windows Server with Desktop experience. Windows Server 2016 Datacenter Edition is up to date, running on AWS EC2. Isolation is Windows Containers. Networking mode is NAT.

Any ideas how to troubleshoot?

The nat network is much slower on Windows Server Docker. Create a transparent network in Docker instead, and use that if possible, and you will see much improved performance.