Slow DotNetCore 2.0 MVC after publishing in IIS

Question

I have a website that uses two MVC web services. The entire project, both services and the website, were developed using dotnetCore 2.0 MVC and Angular

I am using VSCode for development. When I run VS Code in the debugger - (I think it's Kestral?) Everything is fine. A website (AngularJS) calls service A, service A makes a bunch of calls to service B, and everything responds very quickly.

OK Now I publish "dotnet publish" and move the output to be hosted in IIS. Everything works, all calls are successful. However, calls from service A to service B take a few seconds. Where on the DEV server they only take a few milliseconds on the PROD server, the same call takes a few seconds.

If I call Service B from the website, the answer will be as expected - very fast.

So, to summarize - The Service Call Service B on the DEV server with the launch of VSCODE debugging is very fast - Service. Calling service B on the PROD server with the published version of the project working for IIS is very slow - Calling AJAX directly to service B works fine even in the published version of IIS.

Does anyone know what could be causing this. Or even where can I start debugging a problem?

Thanks in advance.