HTC EVO 4G :: SD Card Loading Times

I think this issue is correlated directly to the SD card that comes with our phone... but it seems to be quite slow. I say this, because I notice quite often that my music has short to medium pauses between tracks (off the SD), and if I do anything else while it's playing back, like say.... downloading something through the browser (I use Dolphin, everything is set to save onto SD as well as the cache) my music will skip and jump mid-playback. It's been like this since I got it, and it's been getting worse the more stuff I put onto it. I know that it's normal for any storage drive's write/read speeds to drop proportionately as the free space is taken up by data, but it's starting to become an issue with what I would consider 'normal' usage. The SD card we got with the phone is only a Class 2, but I've yet to have these kinds of problems with any other class 2 cards. Should I get a Class 4 or 6 and see if it fixes the problem? (money isn't really an issue, I just don't want to be paying $115 for an SD card. Hell, I could get a 500gb HDD for my computer at that price!)