Acrobat 9.3 freezes while scrolling

Question

I work with a person who keeps track of his work on PDFs by marking them up.  He keeps the document open almost constantly.  As long as the document sits open, Acrobat.exe slowly takes up more and more memory on his computer.  Whenever he scrolls the PDF, if he scrolls by more than a page, Acrobat hangs for a second.  When Acrobat returns to normal, Acrobat.exe's memory usage has jumped by about 20 MB.  If he keeps the document open for more than an hour, the way he typically uses it, Acrobat.exe's memory usage will typically grow to over 150 MB.  I know Acrobat has memory leaks, but I don't recall it normally being that bad.  Is there some setting that can be turned on to fix this?  Acrobat's been removed and reinstalled.
Acrobat version 9.3.1
Windows 7 64-bit

Answer 1

Unfortunately, updating is not an option.  The person cannot update Acrobat because it would violate organizational policy.  He is locked in to Acrobat 9.3.1 for the foreseeable future.  What other options are available?