Converted sounds are sounding bad.
The converted sounds are sounding grainy. Go to the options and set it to use the "best suited format" under the Decode Format area.
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!