High Spin Time detected for Windows Fibers

Hello,

I recently switched from VTune Amplifier XE 2011 to the 2016 version.
With the new version I see substantially different profiling results (regular Hotspots profiling) compared to the old one.

The 2016 version reports a high spin time (and more effective time) for functions SwitchToFiber and SwitchToThread, while the other functions show far less effective time than before.
The program I'm profiling is using Windows Fibers quite heavily, so it is not surprising that SwitchToFiber shows up in the profiler, but the high spin time is unexpected since Fibers are implementing only co-operative multitasking.

Any ideas?

Thanks,
Thomas