If you are having trouble with a slow internet connection with your wireless airport card, you might want to upgrade firmware-b43-installer or firmware-b43legacy-installer, depending on what you use. It has to be either b43 or b43legacy. I ported an older version (019-3) and renamed it to a version later than 019-8, so it can be automatically installed by people who have 019-8 already running. To get this package:
sudo apt update
sudo apt upgrade firmware-b43-installer
Replace firmware-b43-installer by firmware-b43legacy-installer if you use the latter.
If you have both packages installed remove them both and install only the one you need. See the installation instructions for more information about wireless connections.
You can also look at the airport page.