[HappyCatMachine]

This seems to be happening with many apps that use this memory hogging method for handling files on the iPad 1. Pages, Keynote and Numbers also have severe lag issues with returning to catalogues of files.

This is relatively recent and did not involve an OS update. I've found that closing down other apps, restarting the iPad and the like temporarily fixes the problem. The iPad 2 seems unaffected by this issue but then I've not had a lot of time with it yet.