Chrome throttles tab CPU activities when backgrounded, but doesn't clear memory for the tab. For users like me who usually have 50-800 tabs open across all my browser windows, that really adds up. I also appreciate (err... appreciated) The Great Suspender because I didn't want all of those tabs active every time I opened a browser, so I'd have scores of tabs that never even got loaded, but were ready to go the moment I wanted to return to them.