One way to reduce image sizes is through the use of Adobe Photoshop.
In Photoshop,
Click on Image, Image Size, reduce the document width to something like 6"
Click on File, Save for Web, change Compression to Maximum
save the new image. (I'd suggest a new name so you don't overwrite the image)
This can reduce an image that started out as 400kb to something like 110kb.
Good Luck!
Mike
PS. Good idea creating this post Steve!