Want to upgrade to CS6, but issue with AVCHD scrubbing might stop me

Question

I've been using the Adobe Creative Suite for years and really love it. The last version I stuck to was CS5. Premiere Pro CS5 had no problems scrubbing my AVCHD footage (mts wrapper from GH2 cameras) and I wanted to upgrade to CS5.5 when this became available. Then a problem occured: although the project files (old and new) loaded a lot quicker than before, it was no longer possible to scrub through the footage. The lag was just incredible and I can see (and hear) my drives go mad as I try to scrub through the footage. I assume this is because certain things are no longer loaded at the opening of the project, but just when you look at the footage on a timeline.
I hoped the issue would have been fixed in CS6, but after a colleague kindly installed the software for a few days on my machine (spare licence he had, since been uninstalled), it is clear that it is still impossible to use. WHY?
I'm happy to upgrade some of my system to try and make this work, but I need to know what the problem. My current set-up is (no longer) cutting edge, but hardly bottom of the pile either. Any advice would be appreciated.
Current Spec:
6 core AMD processor 3.6Ghz
8 GB of ram
Nvidia GT440 card (cuda enabled)
MTS files and project files are on a 2TB raid 0 (though windows 7, not dedicated card) (2 drives 1TB each 7200RPM sata 3)
Thanks for any help.
PS: I tried with and without cuda, moved the media cache to other drive, disabled sound whn scrubbing,... pretty much everything

Answer 1

Niels,
I've seen them and will add them to the results page later today.
You end up around rank #630, somewhat as expected. Your disk score is quite acceptable and reflects your raid setup. However, your MPEG score is disappointing, but that may be attributed to only 8 GB memory and the relatively meager GT 440 card. However, in comparison with other Phenom II X6 systems, nothing really stands out.
Your dilemma to improve the scrubbing behaviour is twofold: You are hindered by the slowness of the Phenom II X6, and whatever you will upgrade, but keeping the AMD CPU will only marginally improve performance. If you really want to improve performance you need a completely new Intel based system, but that is costly, requiring a new CPU, mobo and memory.
Upgrading memory does not look attractive, since it will not really help performance and is not portable to a new Intel system.
The only things that can help IMO and that can be ported to a new system in the future are extra disks and a better video card. I would start with additional disks, see if that solves the scrubbing issues. If that still is not enough, you can consider upgrading the video card to a GTX 670 or even a GTX 560 Ti if your PSU can handle it.