Deactivate Flash in Firefox

Firefox can cause high amount of CPU-load when displaying multiple tabs with flash content. A very nice little plug-in for Firefox is Flashblock (must be good, considering it's name ;). You can either download it from the developer's website, or via the firefox addon-page. What it does is initially replacing every flash animation on a web page you load with a little spacer. Clicking on the spacer loads the appropriate flash movie. The effect is that it dramatically reduces the CPU load, as it suppresses all flash movies by default (a nice side-effect is that lots of adds disappear, as they are often implemented in flash). It also supports a white-list of pages on which flash should be loaded as usual, so you can add pages like youtube.com if you don't want to click on the spacer every time.