Conversions are taking a long time.

Go to the options dialog to set the pauses to a shorter time. 50 - 250 millisecond pauses are a good setting. For maximum speed, you can set it to 0 millisecond pauses if you don't need to do any other processing on your computer!

In addition, it is natural for conversions to WMA and MP3 to take longer than converting to WAV.