This post is the hardest for me to write as I generally pay little attention to disks. When they prove too slow, I replace them with faster ones. So now I am writing this on laptop with two SSDs. That said, Disk subsystem could be a major system performance bottleneck and thus there are numerous counters covering this area (Get-CimClass *disk* | Select CimClassName). I would also like to turn your attention to old yet excellent article Top Six FAQs on Windows 2000 Disk Performance if you're interested in subject.

Disk counters:Note: Microsoft recommends that "when attempting to analyse disk performance bottlenecks, you should always use physical disk counters. However, if you use software RAID, you should use logical disk counters. As for Logical Disk and Physical Disk Counters, the same values are available in each of these …