Generally, I've noticed that when I either format my HD or reinstall AH for whatever reason...the first few times I run the game I'd get minor hiccups when encountering new planes at a distance. I attribute this to loading the skins. Eventually, either through defragging the hard drive or the skins getting loading into memory cache (or something), the freezes disappear. I run everything max with 1024 textures on a C2D 2.66ghz, 8800GTS 640, 4gb ram, and RAID 0.