I don't know if this still applies, but AHI v5 used to crucify any genuine 680x0 you could throw at it. v4 seemed to be a lot less CPU intensive on 040/060. We are talking the difference between 5-10% cpu time on my 040+Paula for v4 versus 40% or more for seemingly the same output quality on v5.
Next up, I seem to recall there were some fixed point (read integer) versions of the mpega.library. Although the 060 has reasonable FPU speed, it also has two integer units. I imagine a properly written integer version of the library would be faster.
