I've looked a bit deeper into this problem and this is what I found:
- DPC latency issues are a problem with ALL Windows machines. This is due to the fact how Microsoft has built their NT kernel, where drivers cannot process data immediately in their interrupt routine, but rather has to schedule a Deferred Procedure Call (DPC), which is basically a call-back routine that will be called by the operating system as soon as possible. This by itself is a problem with real-time audio, and this is only enhanced by sloppy, lazy or just plain bad driver programming by lots of manufacturers.

- Since Intel Speedstep (or AMD's cool 'n quiet) CPU trottling has become mainstream, especially with laptops because battery-life is considered more important than raw performance. This means that, with a PC laptop, you hardly ever reach the advertised speeds of your CPU. Usually 10 - 20% less. Most manufacturers of laptops also don't include the option to disable it in the BIOS for this reason. Most people will never notice this however, since they simply don't know and only do desktop applications work or gaming with their pc, two applications where you'll never notice DPC latency issues.

There's only one manufacturer which doesn't suffer from these problems, and who does value the performance of their machines, and that's Apple. The fact that their OS is based on Unix helps a lot with this, which brings me back to this quote by Peter:


Because we all know our beloved Empeg ran Linux, and for good reason it seems now. This is probably also the reason almost all audio professionals use Mac because they know Apple does optimize their machines for real-time audio applications.

In short: I should probably invest in a Mac again, and I probably will. Traktor support hinted me in that direction as well, and they are right. Linux would have been good as well, but Traktor doesn't have a Linux version of their program.