The visuals should not appear sluggish in tuner mode. Please be more specific about what you mean/which visual you were watching/exactly what was sluggish about them.

The data is sampled at 29400 from the tuner which is effectively an analogue stream at the point it is sampled. You should notice a minimum of 1/38 second delay, and a maximum of 1/19 second. In theory you should never notice a delay of more than 1/38 seconds. During mp3 playback the data is delayed which means you don't even get the 1/38 second delay.

Unfortunately because of the way the thing is wired up tuner sampling is volume scaled by the overall player volume, you may find that you get better results with the volume set to 0db, as at -30db the signal is 1/1000 of the original. The code automatically gain controls the input signal, but if that is very small, then the results will not be good.

Toby