Macs get dirty too. Just like any OS, there's tons of files that pile up from daily use, unbeknownst to the average user, which you will most likely never need. These files just waste space on your Mac, and there are many solutions out there to deal with this. CleanMyMac by MacPaw is definitely the best looking one. Testing on a PPC and an Intel box, we saw great performance as well with the app.