I currently use Ubuntu 10.10, and I find the emulator extremely slow. However, I have an Intel Core 2 Duo CPU (T5200 processor) with 4G of RAM. What do I need to improve performance? Better hardware? A minimal Linux distribution?
Unfortunately the emulator is extremely slow on all platforms. Better hardware will only get you so far.
Edit: Since there are now native x86 versions of the emulator, performance should be considerably improved. You should be able to get them through the SDK (or through Intel's website, see this Stack Overflow post).