There is a new add-on called PDF Download that was just released in the Firefox recommended add-ons page. What’s great you can find about this add-on is the control mechanism of this software; it allowed users to decide how they want to deal with the PDF files in Firefox browser. In their own words, this add-on enable:

- Stop PDF files crashing your browser.
- Stop PDF files taking forever to open.
- Make PDF files download like other files in Firefox.

After you download it, click on any PDF file when you use Firefox in surfing the Web, there will be a dialog box prompted you on a variety of choices on what you would like to do with the file: Download it, Open PDF, View as HTML, Bypass PDF Download, or Cancel the action.

Download and enjoy.