The main video files are sitting on a 12TB NAS (file server on a network) that gets 90-120 MBps read speeds. Write speeds seem to fluctuate between 60-90 MBps.
The scratch disks are set to local, non RAIDed drives as follows:
(1) 7200 RPM 1TB for captured video
(1) 7200 RPM 1TB for captured audio
(1) 7200 RPM 1TB for video previews
(1) 7200 RPM 500GB for audio previews. This disk also contains the OS (Windows 7).
All media cache is going onto the last drive also (the one with the OS).
I understand from asking around that the captured video/audio doesn't really mean anything anymore if you're not running tape-based media. We are all solid state...
Already read your setup on another forum.
Your NAS is likely to cause this problem. The speed of the NAS is lower than a single local disk, so you get performance that may be less than in the case you had only 2 disks locally, one for OS & programs and one for editing. This is the absolute minimum requirement set by Adobe, but they always understate minimum requirements. With larger projects more disks are required. Since there is some overhead for Windows in using a NAS, that does not help either.
You could try to configure a 4 disk or larger raid0 locally and see if that solves your issue.
Also have a look here: Adobe Forums: Generic Guideline for Disk Setup
Updated to 5.0.2 yet? It specifically addressed this issue.
I updated to 5.0.2 several weeks ago. I currently have everything updated--just checked. I have version 5.0.2 (075 MC: 218798).