Let's write a few notes about benchmarking the different mp3 decoders, which are available. 'top' is NOT a benchmark, it's a simple check on how a program performs. The sad thing with 'top' (or better the linux kernel) is, that it has some problems with the measurement of threaded programs or programs only requesting short chunks of processor time. One real test is to measure how long your machine needs to decode a stream without threads with 100% CPU. Using mpg123 you can do this with
time mpg123 -t mp3stream.mp3
or, if you additionally want to measure the I/O time:
time mpg123 -s mp3stream.mp3 > /dev/null
If you find a player, which claims to be 10 or even more times faster than the current players: just don't believe it. A factor of 2 MAY BE possible.
This is using the benchmark-cpu script in the SVN trunk. The user CPU time of mpg123 decoding the whole album Points of View by Convergence (get it from Jamendo) has been measured. We are working on some nice presentation, for now you can have a look at the text files in the benchmark directory.