Performance benchmarks for several Millicomputer CPUs are being measured by several Homebrew Mobile Club members at our wiki.
The benchmark used is an old simple CPU benchmark called nbench, which is basically the original Byte magazine benchmark collection from ten years ago. Its very easy to get running. I looked at the industry standard SPEC benchmarks, but they are more vendor oriented and are not freely available. They don't have any useful results posted for ARM architecture systems.
At this point the results are hard to compare since the compiler options in use are somewhat varied and results for recent enterprise server CPUs have not been posted.