Over the past couple of years it has been increasingly difficult for the average customer to tell what the CPU performance is based on the CPU part number. Of course clock speed is no longer the only factor with new multi-core processors, increased cache sizes, die changes and power management enhancements.
Passmark Software has benchmarked over 10,000 processors. Here is a table of common processors showing their benchmark performance against each other.
To see all CPU Benchmarks from Passmark Software Click Here