Not sure but this is a good question for Microsoft.
That certainly is a good question for Microsoft, but those 3% figures are child's play.
I have word open curently with what is admittedly a fairly large file (21,000 words), but even when I am not doing any work on the file word's CPU usage is up at 40-45% CONSTANTLY. My system frequently enters disk access loops that bugger the system up for about 3 minutes, and invariable when I quit word everything runs smoothly with barely any user CPU usage and no weird disc accessing. Why on earth does word demand such copious resource usage even when it is, to all intents and purposes, idle?
I have said it before, but I will say it again, Word is the only application on OSX that ever gives me problems, and all it ever does is give me problems.
What on earth is going on with this application? Are there any prreference setting that might reduce it's appetite for CPU time? Of course, with it's propensity to crash I am reluctant to turn the save options off.