I had a low performance problem with HTTP requests on .NET. The HTTP GET request to a REST API on the localhost took about 500 ms to complete. I spent a lot of time to fix i
I wrote HttpClientHandler, and in the handler just before the request I deleted the header "Connection". In this case, it sets the default "Connection: keep-alive". Even if before that you put it in the HttpClient by default, set properties, etc. Check your handlers.