Vive VR FPS Issue

Hey there!

i've got an issue with my Vive in Unity. It occured a few days ago and i've got no idea how to fix it.

While in Play Mode, Unity drops the framerate every now and then from about 50-60fps to 15fps or lower. While this happens, the Vive default screen pops out. You know...this Moon, Planet, "this is real"-screen. Also SteamVR shows, that unity.exe is "not responding...".

So I first thought, it's a lack of performance, so I took a shirt view:

After some research in forum, i've got the impression, that some people also facing a similar issues with these drops. There's obviously a correlation between these drops and a very performance hungry task within the "other" section on the CPU and also the GPU. Unfortunately i wasn't able to figure out which one.

Also my Scene is not very performance-hungry due to some basic light rendering and stuff. While playing it on the Screen without VR i've got 100+ fps. (VSync is switched off, due to some hints, that i've got from the Forum). I've already updated every driver from the Graphics card up to the Vive Base Station. I tried several things to reduce render-time (i.e. disable dynamic lighting, disable scripts, ...). Nothing worked out properly. Actually nothing had an impact at all.

I'm quite sure, that it's not a lack of performance of my machine. I've got a gtx970, plenty of RAM, a 3,4Ghz i7 and a SSD attached to a PCIe Port. Also the SteamVR Benchmark test says, that its sufficient for VR applications. Is it possible, that theres a bug within any kind of VR Software update, which came out like 7-14 days ago? Unfortunately, i wasn't able to figure out the release notes for any kind of related software.

it would be great, if someone facing similar problems describing his problems. Maybe there's a hint how to get rid of this.

Or maybe somebody has already solved this.

greetings.