I'd recommend downloading the raid add-on pack here: http://www.downfallguild.org/Downfall_Raid_Addon_Pack so you can be familiar with our setup.  I think you'll find that the decursing we have to do on certain fights/Hyjal trash waves will be MUCH easier with Grid set up for your raid frames.

At first glance it doesn't appear that you've got macros for any of your spells, ie popping trinkets tied to your fireball.  If you're really on top of manual popping, you'll do ok, but the macro is just easier.   Check out http://www.downfallguild.org/node/111 for some help.

Also, you mentioned having some possible performance issues with your computer.  I guess you may have WoW windowed for the screenshot only, but you'll probably see much higher performance if you rull full-screen mode, or at least full-screen windowed mode.