One possibility would be to have a web service carry out the hard work and make gPodder only "read" the data from the webservice without any heavy lifting done. This would make things really (I mean, really, really!) fast (in terms of checking for updates), but would of course make gPodder dependent on such a web service.
Have you tried the latest Maemo version (0.13.0) of gPodder yet? If so, is it just the parsing speed of feeds thare you don't like? How would you like gPodder if parsing was blazingly fast (with the added dependency on a web service)? Thanks for your feedback!