I'm trying to upload a collection of books to my Kindle using Calibre and its resource usage is through the roof:

While its usage of all my cores is impressive, this may be a bit extreme. Is there any way to limit the amount of RAM/CPU that Calibre can use?
Turning off several other programs (and no longer adding more books to the conversion queue) the memory usage drops slight. Still the three calibre-parallel.exe *32 processes each use up a complete core. As for the memory usage, for all four processes combined its totals in around 2 Gb, which I honestly think is a little massive.
