Slow HD video whilst editing I use Adobe Premier 5.5 to edit my videos. I have always seemed to have slow editing.  I upgraded the PC which now has

8 Core
16gb of DDR3 2333mhz ram
1gb 460 gpu
6 hard drives, 1 is SSD


So, I think that it's my hard drives which are slowing everything down. I wonder if the amount of HDD's I have that is slowing it down, even whilst on my SSD it's still visibly lagging.
If you have a 8 core CPU I'd bet it is a fast one too, so that shouldn't be a problem. 16 GB is more than enough for HD, and DDR3 should ensure the speed.
The GPU shouldn't have much to say as long as it's not crap.

If you have 6 slow harddrives, it would be a bottleneck. You should have at least 7200 rpm disks!