My main music library is on my 2011 Mac Mini, 2.3GHz 8G ram Core i5 CPU. Right now it is half way matching my 9000+ songs. Looking at the activity monitor, it is using up one entire CPU, with 35 threads and about 500 Meg of real memory. I assume the matching process is some sort of checksum computation and then a network query, which is why it is CPU intensive but not network intensive.