Performance hit with viewgroups/undocked windows and Windows10

[Crj700Lutz]

Hi folks,
since b/o Novmber I am facing a sudden massive performance degredation in frame rates when using viewgroups.
Before that I had no issues at all, everyhting was running fluently with Frame rates allway above 25fps even in high complex sceneries with UT-Live and and and installed.
Since I could not overcome the issue, I started setting the system up from scratch, but still unable to solve the issue.

What I observe is a decrease in fps by 50-70% when switching from viewgroups disabled to viewgroups enabled, which means framerates of less then 15fps in some areas.
I also observe stutters in little more complex sceneries for about 1-2 secounds from time to time.
The complexity of a scenery does have an overall expected impact on frame rates but...
The position of the sliders (Details/complexity) don't really make a big difference. Even with minimum settings I the pretty much same low frame rates with viewgroups ebnabled.
Load of the GPU is pretty low (13%).
Load of CPU Core 0 is @ 100% no matter what I do. The load of the other cores is fairely low. I experimented with the affinity mask, but also that did not change anything.
Same happens even with Immersive Display Pro unsinstalled.
I read through a couple of Posts (e.g. massive Performance hit) and tried what others helped, but no success yet.

Any hints highly appreciated, how to overcome the issue, appart from moving back to old way (with no viewgroupds but one large Screen).

My HW Setup is:
- MSI Gaming Pro Carbon Z270
- i7 7700K @4.9GHz
- 16GByte RAM @3000MHz
- Gigabyte G1 1080
- Samsung 960EVO M.2
- 2x Optoma GT760 Projectors (1280x800) + 1x TFT (1024x768)

My SW Setup
- Windows 10 with latest updates
- latest Nvidia experiance / Nivida Drivers
- P3D v4.4
- Immersive Display pro v3.04
- FS Global Ultimate NG
- ORBX Vector/Global/Europe + ...

My feeling is, that it might be related to a Windows 10 October release.
Please let me know whatever type of additional Information might be required.

Thanks a lot in advance