Yeah, expanding WebMs inline is probably not the smartest idea. Someone made a video of them browsing a WebM thread in Firefox with the task manager, and Firefox swiftly growing in the gigabytes of memory usage until it ran out of address space (Firefox is still 32-bit only on Windows) and crashed. They will probably need to change the inline extension to automatically close videos after some limit has been reached.
Firefox's implementation of gifs isn't exactly sunshine and roses either. It appears to keep animating gifs in the background, even if they are in separate, not selected tabs. For one, you can see the tab icon animating pointlessly. More importantly, this uses up a surprising amount of CPU. All the time I hear my laptop's fans start whirring, and see that all of my cores are pegged at 20-40% (on a Sandy Bridge i5, mind you, not some toaster). When I realize that I have some gifs open and close those tabs, it immediately drops back down to a normal 0-2% usage idle.
Firefox's implementation of gifs isn't exactly sunshine and roses either. It appears to keep animating gifs in the background, even if they are in separate, not selected tabs. For one, you can see the tab icon animating pointlessly. More importantly, this uses up a surprising amount of CPU. All the time I hear my laptop's fans start whirring, and see that all of my cores are pegged at 20-40% (on a Sandy Bridge i5, mind you, not some toaster). When I realize that I have some gifs open and close those tabs, it immediately drops back down to a normal 0-2% usage idle.