Perhaps you can make another stab at explaining what's happening... you
begin by saying "Outlook slows down when I try to use the track changes
feature in Word 2007." Then you say "I have tried closing the document and
making changes with the track changes feature on..."
First, what's slowing down? Outlook or Word?
Second, once you've closed the document, how can you then make changes to
it?
Can you see why this message is confusing?
Once we get past that...
What are the symptoms? "Slow" could mean a lot of things, and quite
different things if you're talking about Outlook as opposed to Word.
Other basic questions include how large the document is, whether it's
located on a server, how many other programs are open, what operating system
you're using, how much memory your computer has, whether you're using
add-ins in Word that might be slowing things down, and whether your computer
has enough free disk space to allow for however much virtual memory is
required for what you're trying to do. (Word 2007 does use more memory than
Word 2003, so it's possible that you're hitting resource limits.)
For what it's worth, when I first started using Word 2007, I found that the
Adobe Acrobat add-in for Word slowed word down immensely, but it was not
related to using track changes. Still, at the margin, the extra resources
required could be pushing your computer beyond comfortable processing
capability.