I don't get so much sluggishness, but the first time I listen to a track the empeg is very susceptible to crashing at the slightest excuse (and it reboots if I use hijack to change info display types unless I wait for about 2 minutes after boot up)
I do only have the II - so lower memory may be an issue. Waiting for my new 20Gb Mk 2a - maybe it'll help:)