Running apt-get on an SD card-based Debian system can be time consuming, since write processes on SD cards are time costly (depending on the card’s speed) and apt-get may do a lot of writing. The first solution that comes to mind is setting up a ramdisk, however in my case RAM is a limiting factor (Futro S400 with 512MB RAM). Instead I used NFS (nfs-kernel-server in combination with avahi-daemon for name resolution) to have parts of the writing outsourced to network directories, mounted from a server with fast storage (hard disk instead of SD card):
In the server’s /etc/exports:
/var/lib/apt/lists remote.local(rw,no_root_squash,no_subtree_check) /var/cache/apt/archives remote.local(rw,no_root_squash,no_subtree_check)
And in the remote system’s /etc/fstab:
server.local:/var/lib/apt/lists /var/lib/apt/lists nfs4 server.local:/var/cache/apt/archives /var/cache/apt/archives nfs4
With this method I managed to increase the speed of apt-get update and apt-get install by a factor of 10x.