RX2 start lagging only after openning a playlist.

Like the title says. I've been playing with this unit for almost a year now. I typically just scroll through my entire library of about 4000 songs, with occasional search. I play stand alone off of a samsung 124gig bar USB thumb drive. I recently started sorting things into playlists because I got tired of scrolling. Now when I load a playlist I get a waiting icon that lasts from 1-6 seconds every time I go back to browse tracks. This problem persists even when I move back to my open collection. It even got to the point one session where it would sit an spin indefinitely when I tried to search. Even scrolling starts lagging and I have to click slowly one at a time or it freezes and jumps. The problem fixes its self once I restart the device, but as soon as I use a playlist it starts again and gets progressively worse. Any suggestions?