Megahertz or gigahertz
A better unit is OPS (Operations Per Second) or FLOPS (FLoating point Operations Per Second). However benchmarking CPU performance is a tricky art and there are many different speed benchmarks (each with its own advantages and disadvantages):
- Whetstones (for floating point speed)
- Dhrystones (for integer speed)
- Livermore Loops
- linpack
- Tak (for recursion speed)
- etc.
Ultimately, the best benchmark is the actual application you want to run with your actual data being processed. But this is rarely practical on actual projects.