OMG, thank you, ChicagoBubba! iTunes' laggy podcast list view has been driving me nuts for months. Also, the network bandwidth meter was taking a jump into the several Mb/secong range every time I so much as opened list view, almost as if iTunes was sending and retrieving library content to and from a server.
So first I shrunk the iTunes window to the smallest possible opening before selecting the dreaded list view. Then quickly hit command-j, and unchecked "show artwork." Instantly the bandwidth meter went to near zero, and the list returned to scrolling all smooth and supple like it's supposed to. Yeah, it's a bummer not to see the artwork, but I'll take the trade. iTunes was evidently trying to continuously reconcile album art.