~85.5% of native code when profiling with Jet Brain's dotTrace?
It is a normal situation in case of profiling a web application hosted on IIS as IIS is a native application itself. So if all of your app's methods are presented in a snaphot then you have nothing to worry about.
See this page for details: https://www.jetbrains.com/help/profiler/Profile_ASP_Web_Site.html
"Note that it is normal that the snapshots contain large amount of native code"