PDF file format, as ubiquitous as it it, can be bloated with large file size especially if is generated with tool without compression. Preview for OS X has a build-in feature that can help to reduce the PDF file size.
Open the PDF file in Preview and select from menu File > Export. From the “Quartz Filter” drop-down list select “Reduce File Size”. Key in a different file name in “Export As” if you do not want to overwrite the original file. Click the “Save” button to export the PDF using the file size reduction filer.
We are able to get the “iPad 2 User Guide” PDF file from Apple to slim down from 17 MB to 6.5 MB. How much space you will save varies greatly and depends on the PDF file content as well as the tool that is used to generate the document.