While idling in #archlinux on freenode, I came across this neat little trick to speed up downloads in pacman.

First install the package axel:

pacman -Sy axel

Then, edit /etc/pacman.conf:

XferCommand = /usr/bin/axel –output=%o %u

The next time you update/download a new package, Pacman will now use axel to download the necessary files.  Axel will try and make multiple connections thereby taking less time overall to download.

To install simply add the following two lines above [core] in /etc/pacman.conf

[kde-unstable]
Include = /etc/pacman.d/mirrorlist

then

pacman -Sy kde

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