I just installed Qubes 3.1 on the same hardware, and the performance was "how it should be". Then I made the in-place-upgrade to Qubes 3.2, which resulted in the same problems as I mentioned in the first mail. So I guess its not the Kernel, but some kind of software that causes the problem.
Does anyone use a CPU from the current Skylake-Generation, or maybe even a i7 6700k? I bought the hardware a couple weeks ago, and just tested it with Qubes 3.2, and it quit works. Just the performance is a mess. There are constantly small laggs, which I don't have with an older Core i5 in