There are a huge number of factors that may affect the size of a PDF file. Therefore it is necessary to decrease the PDF file size. The factors that affect the file size of PDF are the resolution of the images, the way in which the fonts are embedded, the type of the image, the level of compression and the version of PDF.
One of the ways through which you can decrease PDF file size is by using the save as option every time instead of save. The save option will save the new changes and hence the PDF file size will increase. While save as decreases PDF file size as it saves only the latest change made to the file.
Excluding name destination decrease the PDF file size. About every ten name destinations will add to about a kilobyte to the size of the PDF file. If you think it is not necessary you can eliminate them in order to help decrease the PDF file size.
Some viewer software for PDF files help in showing you which of the elements in the PDF file occupy a lot of space. By knowing this you can look at different ways to decrease PDF file size. This can be done by selecting the audit space usage option in the advanced menu bar.
Coming to the most important part of the file that adds to the size of the PDF file is the images. Making use of vector based graphics decreases PDF file size. These look better, scale perfectly and take lesser space compared to many others. You can decrease PDF file size by not including bitmap graphics.
Font sizes take up a lot of space. Do not embed your fonts as it will help you to decrease PDF file size. If you are creating PDF files for the web and you do not need to print this then make use of rgb. Rgb has a data channel lesser then cmyk.
One last thing that you would want to do to help decrease PDF file size is to use the versions of acrobat that have come newly into the market as they will have better compression systems.