I am certificated .NET/C# programmer working in this region since 2002. Main specialization is back end programming:
• Creating WEB (SOAP), WCF and REST services,
• Designing databases, creating complex queries, views, functions and procedures for MS SQL server 2008 and later,
• ASP.NET programming, favorite template is MVC but WEB Forms is well known me too.
I will need one week for studying your application and capturing main problem: I worked out many WCF services with binary TCP/IP binding and had no complain on slow work. Direct socket programming is not needed in most cases, but I am able to fix it using Windows API. I think that main reason of low speed is dirty database design and usage of Linq or nHibernate.
I shall pass your application over profiler and send you my proposals after capturing the problem.