For reference purposes from the Intel N2820 NUC when using the Linux 3.15 kernel loaded on Ubuntu 14.04 LTS 64-bit, I compared the performance of the ACPI CPUfreq and Intel P-State CPU frequency scaling drivers. With the P-State driver I tested only with the performance governor as the powersave governor locked up the system. With ACPI CPUfreq I tested the Celeron N2820 with the powersave, performance, conservative, and ondemand scaling governors.
Read the earlier Phoronix article for more background information on this testing along with some power consumption comparison numbers, etc. To see the results, all of the system information and benchmark results in full via the Phoronix Test Suite are hosted on OpenBenchmarking.org via 1405297-KH-INTELNUC248.