Is your Ubuntu works slow just after the login or when your backups running?
it’s may be because Dropbox or DejaDup (called ‘Backup’ in Ubuntu) are doing a lot of raeding from a drive.
This two commands solve all the issues, making both programs run with as low priority as possible.
Making Dropbox friendly (especially if you have over million files in your Dropbox folder):
ionice -c 3 -p `pgrep dropbox` renice 20 `pgrep dropbox`
Making DejaDup/duplicity friendly
renice 20 `pgrep duplicity` `pgrep deja-dup` ionice -c idle -p `pgrep duplicity` ionice -c idle -p `pgrep deja-dup`
Have fun! and fast working computer