The Page Files Sizes section in the Page Components screen contains a brief overview of the make-up of your current page.
The information listed includes:
Overall Page Size (In kilobytes) - Remember, you want to keep your page size on or below about 100kb in most cases.
Text Content (In kilobytes) - Gives you an idea how much, of the total page size, is accounted for by text content.
Image Content (In kilobytes) - Indicates how much data, cumulatively, is attributable to images in the current page. If you notice that you have a page size over 100kb, and/or your images are of substantial file size then you may wish to compress your images using a graphics package (such as PhotoImpact, or Photoshop) so that they are better suited for use on your Web site. Often, such image compression can dramatically reduce your image file-sizes yet without perceivably altering the quality of the image to the viewer.
Above the Page File Size pie-chart is a small button labeled 'enlarge'. Clicking this button will load a new window with an enlarged view of the graph within it.