If you find that application designer or data mover is taking a long time to load, it could be because tracing is turned on in your configuration manager settings. A good indicator that this is the case is to browse to your temporary files directory (%TEMP%) and look for a file called DBG1.TMP. If this file exists, and is growing steadily, then the application designer/data mover login process is being traced.
To check this and turn it off, open configuration manager, and browse to the Trace tab:
As you can see, there are a few trace options enabled there! Click on the Clear Trace Settings button (on the right), and press Apply and OK to turn off tracing and close down configuration manager.
You should now be able to login to application designer/data mover.