Re: slow saves

I have had similar problems, seems to come from dwgs from certain sources. I found the problem had to do with layer filters, which don't get purged (except in 2004, I think), and accumulate into your current dwg when you insert dwgs that have layer filters.
Cadalyst mentioned a lisp command that removes all the layer filters, at
Click on Services, then ACAD Clinic Archive, look for Aug. 2002 feature "Layer FIlter Overload".

Thanks Tim! That was exactly the problem. Here is the lisp routine that deletes all of the layer filters. One thing, if you use this, you will have to save the drawing then close it and reopen it in order for you to see the change.
(defun C:LayerFiltersDelete () (vl-Load-Com) (vl-Catch-All-Apply '(lambda () (vla-Remove (vla-GetExtensionDictionary (vla-Get-Layers (vla-Get-ActiveDocument (vlax-Get-Acad-Object)))) "ACAD_LAYERFILTERS"))) (princ "\nAll layer filters have been deleted.") (princ))
(defun C:LFD () (C:LayerFiltersDelete))