I recently have come across many problems connecting to the Airport. It takes a long time to find the network lately. This happens with every computer in my house. Here are a few things you can try to solve this speed issue:

1. Open System Preferences.

2. Click Network.

3. Click Advanced.

4. Drag your network to the top of the list.

5. Click OK.

If that doesn’t work, try the following:

1. Trash the SystemConfiguration folder located at /Library/Preferences/

2. Trash the com.apple.systempreferences.plist file located at Home/Library/Preferences/

3. Restart the computer and try to connect to the Airport again.

These last steps worked for me.

See also: Airport Slow to Connect