.net 5 (and former .net core) was pretty fast. The issue was in serverless there is a pretty long cold start since the interpreter is still invoked which is like a mini virtual machine. If you're sticking to azure, they have a highly customized environment for it that I'm pretty sure saves interpreted output vs source code.

I would highly recommend golang to old school C# devs who are very comfortable with threading, thread safety, and mix of high and low level code in the same codebase.

edit: Best go devs I know are seasoned C or C# backgrounds.