spu stands for Silent Package Upgrader.
It can upgrade installed packages completely in the backgroud.
You will never being blocked by "Contacting host: elpa.gnu.org:80...."
when upgrading package.

You will never worry about packages ugrade
with just one line : (spu-package-upgrade-daily) added to your init file,

See https://github.com/mola-T/spu for more information.