Good results in DirectX 11, but not in Dx 9 and 10 (GTX 970)

[Nantes]

My friend who has a very similar system to mine gets 20+ FPS in "Warhammer - End Times: Vermintide", and his graphical settings are considerably higher to boot! Thus, I decided to run PerformanceTest to see if it was any fault with my hardware.

CPU results seem to be as expected (http://prntscr.com/9mcq5n), but here are my GPU test results: http://prntscr.com/9mcqnm and http://prntscr.com/9mcjyr

The Direct3D 11 results are just as expected (it is known that the GTX 980 has 15-20% more performance than GTX 970), but the others are completely bogus. Could this indicate a software fault of some kind?

System:
Core i7 3770k (non-OC'ed)
Gigabyte GTX 970 G1 Gaming (stable overclock to 1460 Hz/3750 Hz, I disabled the OC and the test results were a bit lower)
GeForce driver 359.00
12 GB RAM
Samsung 850 EVO SSD

P.S: I have asked my friend to also run PerformanceTest and I'll post his results later.

[David (PassMark)]

The DirectCompute & DX11 results seem reasonable.
DX10 result is so so, but not totally out of the expected range for this card. But the DX9 complex result is way down.

If you run the DX9 complex test a few times is the result consistent (about 29 frames per second)?

Did you check the CPU/GPU temperatures?