That's because you skipped step 2 of the instructions.
First, you're running Flash. Flash is notorious for consuming system resources, raising temps and decreasing battery life. For Flash-related issues:
- Find your Flash version and make sure it's the latest version available. Never install or update Flash from a pop-up on a website. Always go to Adobe's site to get Flash or updates.
- Install ClickToFlash (Safari), Flashblock (Firefox) or FlashBlock (Chrome) to control which Flash content plays on websites.
- Try using the YouTube HTML5 Video Player to watch YouTube videos, when available. (May impact fullscreen viewing. See link for details.) Some have reported better performance with HTML5, while some have reported worse. Try it and find out what works best for you.
Second, you have significant page outs in the System Memory tab. To determine if you can benefit from more RAM, launch Activity Monitor and click the System Memory tab at the bottom to check your page outs. Page outs are cumulative since your last restart, so the best way to check is to restart your computer and track page outs under your normal workload (the apps, browser pages and documents you normally would have open). If your page outs are significant (say 1GB or more) under normal use, you may benefit from more RAM. If your page outs are zero or very low during normal use, you probably won't see any performance improvement from adding RAM.
Mac OS X: Reading system memory usage in Activity Monitor