App eats memory when HMDUnmounted (Windows)

When my app runs and the HMD is mounted/the sensor covered memory is staying steady(over hours). When i unmount memory gets eaten away until the app crashes ~ 1GB RAM/5 minutes. Is there a memory leak? Or do i have to handle the situation in any way? My installation consists of 5 rifts dangeling from the ceiling in a museum, so there will be quite some Unmounted-Time. Is this a known limitation/bug?

Windows10/64, Runtime 1.7, Unity 5.4.1f1