You can install the LiteRider7 add-on from the Mozilla add-ons website. The installation of this add-on requires you to restart the web browser and it can be used immediately after the restart. After the restart, you would see a new menubar appended next to the Firefox menubar. If you have not made the menubar visible, then you have to make it visible by selecting Firefox → Options → Menubar.
So if you are sick and tired of waiting for a website to load while it is busy downloading tons of images that you are not even faintly interested in, then you can use the LiteRider7 add-on. This add-on would make browsing the websites very quick and efficient. At the same time, it is very useful when you are preparing to take the printouts of webpages which are rich in unwanted pictures.
You can download and install the LiteRider7 add-on from https://addons.mozilla.org/.