As playback is very heavily dependent on I/O, I'd look at your HDD setup for this. Though you have 2 very fast HDD's and they are in a RAID 0, there can be a lot of read/write going on with what the OS sees as one HDD.
I'd also bet that you can increase playback performance if you eliminate many of the Proecesses, that are likely also running on your system.
Ideally, if a RAID is used, it is better suited as a media drive, and not the system drive.
There should be some tips in each of those.
Thanks for the help. Any specific processes I should look at turning off? I also forgot to mention that my OS is on a seperate drive and the raid is just setup for media, my project file is saved on 2 mirrored drives as raid1.
Tried it in a HDV project and it loops fine. No problems at all. As Bill pointed out, it may be your disk setup that has trouble of keeping up with things. Do not forget that your disks, even though pretty quick, will rapidly show decreased performance as your fill rate goes up. On an empty disk you may achieve a transfer rate of around 170 MB/s, but when your raid0 is 60% filled, it will have dropped down significantly.
Ideally HD Tach results should look like this on the long test, but will usually not be achieved other than in very rare circumstances.
You could try to see what your results are and post here. It may give an indication whether the disk setup is at fault here.
Thanks Guys. I am actually at work now but I am surely going to try this when I get home later and post an image.