One thing you can try is removing unneeded extra files from your Dropbox folder.
With any sync method, but especially with Dropbox, things can slow down if there are things like backups or large files present which are not needed. (We sync everything in your Dropbox folder.)
Another thing which can slow Dropbox down is if you are using Git in the Dropbox folder. One solution here is to use selective sync to avoid the .git directory.