I'm an idiot sometimes. I forgot that you're using the TMX stuff. Since it's a geometrically placed system, you just need to calculate which tiles the corners of the screen are on and only show the portion of the TMX matrix that are contained within the corner tiles. It'll be a few < or > boolean operations that only have to be computed when the camera or scene is moved. If you have rotation then it becomes much more of a pain, but it's doable.
The mip-maps are kind of a relational decision when it comes to 2d graphics. They will use too much processing power when the maps are small, but greatly improve efficiency when the maps are large. So that we're on the same page, I mean mip-maps to be smaller versions of the textures that you're usually using that replace the visible textures when they're scaled down. They'll be a major pain with TMX probably, but they made my 3d system triple in performance at times. The assets folder size also grows with mips so that's something to consider. I had one 3d level that had over 80 megs of textures... My client wasn't happy about it, but it ran at 60fps on a SGS.
Don't worry about hijacking this thread - it's in an off-topic forum.
The public beta of Spy Tower is less than a week away. It has been difficult to find time to work on it, but so far it's barely behind schedule. I'm exited about it because it's being released and controlled by me so I get to watch it either succeed or die by my doing. If any of you ever work as a freelance game developer, try to get the contract to allow the game to be in your control from pre-design to post-release. It'll save you from lots of headaches and you'll get to make decisions that help the game instead of following the decisions of (ignorant) clients that ruin the game entirely. I've really put myself into Spy Tower and it's a great feeling.
