iTunes CPU usage while downloading

So, what’s with iTunes 7 using craploads of CPU while downloading on my Mac?

Last night iTunes was downloading two video podcasts on my G4/733 running latest 10.3.x. iTunes alone was using 30-40% of CPU. At the same time I was transcoding a 170Mb video to view on my PSP using ffmpeg, and also scp’ing a 3Gb file from another machine – these two operations were only getting 15% of CPU each.

Transcoding video is obviously a CPU-intensive operation, as is scp (lots of encryption/decryption) – but what the hell is iTunes doing when it’s downloading? Basic transfer of data via HTTP takes almost zero processing power. Is iTunes doing some sort of data validation or transcoding while it transfers? Most of the podcasts I download are already in “iPod format”, so they should be Apple-friendly.

And when a download is complete in iTunes the entire system becomes unresponsive for a few seconds while it does something (copies the file? does more validation? takes a break from sucking unneeded CPU time?).

The machine is a G4/733, so it’s obviously it’s not the fastest Mac around anymore, especially when compared to the new Intel machines, but I didn’t think it was obsolete already. Maybe iTunes is now being written for the Intel platform first and then ported to PPC, and something is missing in translation? Or there’s an iTunes 7 / OSX 10.3.x bug?

Regardless, it’s very annoying.