I've a document here, and that takes about 2 minutes and a half just to save it (on an i5 at 2.4GHz, no swapping involved). It's 113 pages long, with about 30 tables and 15 images, but I don't think that's expected because it took much less time to save when it was, say, 80 pages. So I suspect something triggers a very inefficient code path or something. I can attach the document or mail it if you're interested, but I don't want to post it for days if nobody needs it (it's my Master thesis).
I see the same behaviour here with larger documents on a similar machine, but already starting at about 40 pages. Savetimes are usually between two and five minutes. On top of that, i can't even work on a different document, be it a Text Doc or a presentation, whatever. It's a real PITA when one has to work with several large documents in parallel with autosave on...
[This is an automated message.] This bug was filed before the changes to Bugzilla on 2011-10-16. Thus it started right out as NEW without ever being explicitly confirmed. The bug is changed to state NEEDINFO for this reason. To move this bug from NEEDINFO back to NEW please check if the bug still persists with the 3.5.0 beta1 or beta2 prereleases. Details on how to test the 3.5.0 beta1 can be found at: http://wiki.documentfoundation.org/QA/BugHunting_Session_3.5.0.-1 more detail on this bulk operation: http://nabble.documentfoundation.org/RFC-Operation-Spamzilla-tp3607474p3607474.html
I'm happy for you, because after several minutes document successfully saved. On my computer (Fedora 64 bit, Kde, Intel video, 3.5.1 office) writer hangs if resulting file is greater than 90 Mb.
Dear bug submitter! Due to the fact, that there are a lot of NEEDINFO bugs with no answer within the last six months, we close all of these bugs. To keep this message short, more infos are available @ https://wiki.documentfoundation.org/QA/NeedinfoClosure#Statement Thanks for understanding and hopefully updating your bug, so that everything is prepared for developers to fix your problem. Yours! Florian