For this test I compiled nbench for each board using GCC 4.7. I chose a minimum of optimization settings as the goal was to compare each board and not necessarily produce the fastest results.
|Arduino Yun||Beaglebone Black||Intel Galileo||Raspberry Pi Model A||Raspberry Pi Model B|
|Floating Point Index||0.038||1.591||0.621||2.064||2.002|
Another interesting comparison is the Arduino Yun and Intel Galileo. Both boards run at the same 400mhz clock speed, but it's apparent the MIPS architecture of the Yun has slightly more performance than the Intel architecture of the Galileo. Floating point performance on the Yun is very low because it doesn't have a hardware floating point unit and must run those operations in software.
Finally, both the Raspberry Pi model A and model B are almost identical in performance. This result is expected because there is no difference between the processor on either board. The model B board only has more memory and peripherals compared to the model A. From a performance per cost standpoint, the model A board at $25 is quite impressive.