I can’t say enough about the ClickToFlash plug-in for Safari/WebKit-based browsers.
ClickToFlash is a WebKit plug-in that prevents automatic loading of Adobe Flash content. If you want to see the content, you can opt-in by clicking on it or adding an entire site to the whitelist.
We all know Flash is a resource hog. This cuts Safari’s CPU usage dramatically.
ADDED BONUS in the latest version: Toggle the setting to ‘Load H.264 videos from YouTube’. Doing so will automatically load H.264/MP4-formatted YouTube clips (when available) and play them using the Apple QuickTime plug-in. It is ridiculous to see side by side how much smoother these clips play using QuickTime vs. Flash.
Mega Flash FAIL.