Christopher Baines <mail@cbaines.net> writes:

> It can take a little while to decompress some packages with large xz
> compressed source tar files. xz includes support for parallelism, so enable
> this using the parallel job count for the overall derivation.

I'm guessing this is only suitable for core-updates, as it'll cause a
lot of rebuilds. I'm also not sure if it's worth it, but it does seem to
make building some packages at least start faster.