Bethesda's VP of PR and Marketing Pete Hines has commented on Twitter about Obsidian's project director J.E. Sawyer Formspring answers on an engine-level issue in Fallout 3 and New Vegas that causes slowdowns in proportion to the size of save-game files, which is suspiciously similar to the issue plenty of Skyrim players, especially on PlayStation3, have been encountering recently, but that according to Hines has been long since been solved in this iteration of their technology:
@NotSkyrSpoilers Josh Sawyer did not work on Skyrim nor this engine and his comments don't reflect how the current tech works.
@Elkirak No, it isn't true. He brings up issues we solved long ago.
Whatever the issue is with Skyrim, we hope it will be eventually solved completely by Bethesda, considering the disappointing results of patch 1.2.