"Developer Erik Heemskerk recently published an article describing his investigation into the performance of ASP.NET Core versus WCF. In his experiment, he wrote a simple project that used each technology to "stand up a local web server, measure how long it takes to create a request, send it, deserialize it, generate a response, send that back, and deserialize the response."
Much to his surprise, WCF was roughly 1/3 faster than the equivalent ASP.NET Core project when the payload is a simple GUID. Realizing that the difference may be due to WCF serializing to XML while ASP.NET Core is using JSON Heemskerk forced ASP.NET Core to serialize to XML. This resulted in an improvement, but WCF remained much faster...
Developer Josh Bartley then examined Heemskerk’s work to see what other changes may be made to improve the results for ASP.NET. His analysis indicated that perhaps the benchmarking for ASP.NET was not including the exact same work when compared to the work of the WCF code."
They should have tested Protocol Buffers instead of either XML or JSON.