As Vetinari said: Nothing. The CPU is dual-core and barely loaded by video decoding. Depending on your connection speed and the piece size of the torrents, you

As Vetinari said: Nothing. The CPU is dual-core and barely loaded by video decoding. Depending on your connection speed and the piece size of the torrents, you may run out of RAM though (there's 2GB total in the box and it's quite easy to make rtorrent use that much).