Mark Russinovich at www.sysinternals.com has released freeware utility CPUmon which allows you to investigate CPU performance. Not
for the faint of heart. If you want more detail than NT's perfmon delivers go
for it. Useful to Windows NT admin.
CPUMon is an advanced performance measurement tool. Its combination
GUI/device driver make the wide range of processor performance counters present
on the Pentium, Pentium Pro and Pentium II/III, easily accessible. You select
the two counters you’re interested in, enable them via the GUI, and at a later
point stop the counters in order to see their values. While a measurement is in
progress you can watch the values change with NT's built-in Perfmon.
A utility for your NT Tool box.