DotTrace / Requiring Input generally

Hey community.
One of my products started to behave a bit weird. The application "suddenly" started to react laggy on the UI, while its output remained more or less the same, so I started a profiling session - incl. Windows Performance Toolkit & Symbols.

Unfortunately, even with native allocation collection enabled, the involved native methods couldnt be resolved - but, 98% olf measured ms going on the account of native methods, so something seems to be terribly going wrong at the moment.

Anybody got me an input, how i could further trace that issue down or even got an idea what the hell's happening here?  Do i miss something on setting up DotTrace to properly profile? 

Thankful for every little input