Whenever my time machine backups to a time capsule are decently large, I get transfer rates over wireless of 2-4 MB/s...which seems to be the norm. But what I don't understand is when I only have very small backups taking place (ie if nothing really has changed since the last backup and I get 300kB or 2MB backups) they take much longer to complete than i'd expect given the speeds above. For example it might take 4 mins from 'backing up 2kB of 400kB' until it gets to the end at 'backing up 400kB of 400kB'. Has anyone else noticed slowdowns like this?