According to most of the PDF users, the main factors affecting the size of a PDF are image resolution, image type (bitmap or vector), fonts and how they're embedded, PDF version and the level of compression. The two important things should be looked at when you want to reduce the PDF File size are, removing objects and shrinking the images it contains. Few things to be carried out in order to reduce the PDF file are namely,
Re-create the PDF: Recreate your PDF again and by doing this you can shred away with plenty of unwanted objects, remove tags and compress images further. This can be done with any tool that supports print to PDF functionality.
Use function Save As
If you use a PDF editor like Adobe Acrobat you can use Save As function to reduce your PDF file size
Remove unwanted objects
Shrink all images in PDF files
By shrinking all images present in a PDF can considerably reduce your PDF file.
Further you can also use other utilities in Adobe Acrobat to reduce your PDF file size. It includes following steps:
Use the Save As command.
Make use of Save As command instead of Save command while editing your PDF file. When you use Save command, changes are added to the PDF file that increases its size.
Audit the use of space in the file.
Click the Audit Space Usage button in order to get the audit report which specifies the total number of bytes used by fonts, images, bookmarks, forms, and comments, as well as the total file size. This helps you in identifying which elements are significantly large and needs to be reduced.
Unembed fonts, when appropriate
You may safely unembed fonts if you know that they are already installed on the computers of the people who will read your PDF document.
Remove unused elements and clean up the document.
Remove the elements from the PDF document that you dont need.
Save the optimized file.
Save the optimized/reduced PDF file to its desired location.