I have had similar experience with Word 2013 (15.0.4454.1504) 64-bit, part of Office Professional Plus 2013, and I think I figured out a workaround, or at least the cause of the problem.
I keep an engineering journal document that grows over time each year, typically peaking at around 200 pages in December. The document contains a couple of simple macros and is password protected. I am also a heavy keyboard user and fast typist.
In all versions of Word prior to 2013, scrolling through documents has been fast and responsive, whether I'm using just the arrow keys, CTRL+arrow key, PageUp/PageDn, CTRL+Home, etc. And saving the file with CTRL+S has always taken less than a couple of seconds.
When I upgraded to Word 2013, I found that it has been nearly unusable. I save frequently as I'm typing, and so after I'd type in a paragraph I hit CTRL+S, and at that point the application does everything but freeze up. The "Word is Saving..." progress bar
in the status bar appears, and as of this morning, saving my (now 50 page long) document takes at least ten to fifteen seconds. Worse, while it's saving, if I type a letter or a word, nothing will appear in the document for several seconds, and then a few
letters will suddenly show up.
This has been tolerable, albeit frustrating, but the real problem is the performance when I am not saving the file. Scrolling through text, typing, selecting text; nearly all editing operations are painfully slow.
I found this thread while searching for a solution, and it seems that while many people are encountering this issue, I am not seeing any practical solutions beyond "your system is inadequate" or "your installation or document is corrupt".
I am running on a clean installation of Windows 8 on an HP Z800 Workstation--24 core, 2 socket Xeon with 24G of RAM and a fast GPU, and a fast SSD hard drive. The hardware is clearly not an issue.
Recently I also tried disabling hardware graphics acceleration, which had no effect.
Finally this morning I figured out "a" (not sure if it is "the") problem--my document had been saved in the newer docm format. I did a Save As, and picked the tried-and-true "Word 97-2003 Document (*.doc)" format, and suddenly everything is lightning fast.
I recognize that the old binary format is less secure and perhaps has limitations but in fact it works, Word is now fast and responsive, and I am able to get my work done.
Your mileage may vary, but it worked for me. Something seems to be broken in the new docm handling logic--perhaps it only affects documents that contain macros or are password-protected. But until Microsoft releases a fix it may be worth trying the older .doc
format and see if that doesn't improve things.