My bad.
AFP is the Apple File Sharing Protocol.
Netatalk is the community-based implementation of this protocol.
To help you with this, open up your Mac and navigate to Applications > Utilities > Console.
Open Console, click All Messages and filter out the following three seperate things:
Finder
backupd
time machine
afp
network
Look for any times when backups start and then when they start going slow.
Paste any relevent results, but be careful to remove any personally identifiable information.
-timeimp
