Just in case you haven't already seen this, the slower frame rates are most likely caused by a new frame buffering routine used in the new iPAQ H3800 series. This was discovered by Douglas Beck (RocketElite author) and is discussed here:
http://discussion.brighthand.com/showthread.php?threadid=35445

You can also see the relevant PocketGamer.org news item and comments page:
http://www.pocketgamer.org/archives/00000511.shtml

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Mike
PocketGamer.org - http://www.pocketgamer.org