Hello bcladmin,
try to reduce the JPG to the minimum possible size. For example, if you have a 2MB JPG that you need to reduce to 20% size to fit on you Word background, then use a picture editing tool to scale the image to 20% of its size, save it as a JPG and then insert it as a background as 100% size. That will save on file size in Word.
As a general rule, I prefer to use pictures inserted in the Header instead of background images. Then I can see exactly if I need to rescale the picture, go off and do up the proper size in an image editor and insert the correctly sized image into the header. Set the image to the "Square" layout and you can drag it into the proper position.
With the image in the header, there is no danger of activating the image when clicking in the document body, and it generally works faster than background images.
cheers, teylyn