Chrome: GIFs are a flexible format for conveying short, silent videos. However, they're not very efficient and can be slow to load. A page full of them can become unbearable on slower systems. GIF blocker solves that by turning GIFs into on-demand content.
The extension will replace any GIFs in a page with the above grey box. You can click on the GIF to load it if you choose to, but otherwise it will remain hidden. This is the same tactic employed by many browsers for on-demand Flash content. If you find yourself in a situation where a high volume of GIFs are affecting browser performance.