A PDF document, while very important for various purposes, can get extremely bulky. It is not unusual for a PDF document to become larger than a few MBs even. While that is not a problem for printing purposes, but where emailing and downloading is concerned, the required bandwidth and associated time can become a huge problem. While for modern day T1 and other fast internet connections this is really not a problem, it can be so for the large numbers of dial ups, USB modems and slow broadband connections still in use.
Reducing PDF fonts:
The PDF documents use a large number of fonts that have to be embedded in their entirety in the document itself. Each of these fonts can have a size of 40k or more, and as each extra font family is added, the numbers add up. If you take stock of a PDF document using functionalities present in the Adobe Acrobat software, fonts will come up as a major contributor to its size. Reducing the numbers of fonts used and embedding only those subsets of font families actually used can b used as smart methods of reducing font file size in a PDF document.
Compressing PDF embedded images:
Images that are embedded in a PDF document occupy the largest part of its size. It is a good idea to use the document optimizer utility to reduce the PDF file size. One can also pre compress the images, but too much use of lossy compression methods can create compression artifacts when the image is distilled in the PDF document. Use the integrated optimization utility, therefore, and try grayscaling the image if at all possible. If not, use less color channels (RGB over CMYK) and other methods to reduce the size of the PDF document.