We used iTunes to convert an uncompressed .wav file into a high-quality (160 Kbps) MP3 file, and checked how many seconds each CPU took to perform this operation. Therefore, the results below are given in seconds, so the lower the number the better.
Here the two CPUs from Intel were, again, faster than their competitors from AMD. The Core i3-2105 was 18% faster than the A8-3870K, while the Core i3-2100 was 12% faster than this CPU. The two CPUs from AMD achieved the same performance.