I just ordered this a couple days ago
http://www.newegg.com/Product/Product.aspx?Item=N82E16820208460It is a class 6 and everything loads up on mine in pretty much instantly. I only have 2.5 GB in it and it's a 8GB card so that
may be part of it. I'm thinking the class 6 thing really helps though. To put all that 2.5 GB on the card with the reader it came
with only took about 5 minutes if I recall correctly. With my digital camera and it's lower class card it takes much longer for that
much data. If the class 6 cuts down on the uploading time such a large amount, I would think it would do the same for the time to
read the card and pull up MP3s.
Of course if you also have a class 6 and/or you're filling the card up to it's limit that may be the culprit.