Since version 19 Mozilla Firefox comes with build in PDF viewer.
Generally it does the work and it is really useful when no another PDF reader is installed, but in some cases is not so appropriate and you might be better with external viewer.
Problem I have is that it is Java Script based and even JS is really fast on low power machines it is not as fast as “real” plugin.
In case you need to disable build in viewer do following:
- Open Firefox Options
- Go to Applications
- Find PDF in the list and change the action from Preview in Firefox to appropriate one.
That is all…