First WCF connection made in new AppDomain is very slow

Question

I have a library that I use that uses WCF to call an http service to get settings. Normally the first call takes ~100 milliseconds and subsequent calls takes only a few millisec

Answer 1

You can decorate your Main with LoaderOptimization attribute to tell the CLR loader how to load classes.

[LoaderOptimization(LoaderOptimization.MultiDomain)]
MultiDomain - Indicates that the application will probably have many domains that use the same code, and the loader must share maximal internal resources across application domains.