So what I found out is this: Use the Adblock-Plugin for Safari to block all ads, including flash based stuff, that gives me two or more hours longer battery life. For real, at first I couldn't believe it! Definitely use HTML5 on Youtube. Go here and set the cookie: http://www.youtube.com/html5 When you have done this every video, that is avaliable in HTML5 format on Youtubes servers, will play in HTML5. All other videos will still be flash, though. But most will be in HTML5. That gives me like 5 hours video playback on 720p, instead of like 2,5 hours with flash. Also no heat and no fan noise for your system. I would recommend to simply un-install flash at all, but every now and then, there's something you will need it for. Unfortunately. Hope this helps a little.