Curious. When you say "very optimized Eclipse for Android", what optimisations/improvements would you like to see exactly?
Faster, more responsive, prettier.
So, IntelliJ?
But free.
They have "Back to School" sale on personal licenses. I find 100 euros for an excellent IDE very cheap. It's a different story if you want something open source though.
But it's only for IntelliJ 10/11, and 12 is coming by end of this year (usually).
The free community edition [0] supports Android just fine. I used it for a while for my own personal projects and found it very snappy indeed.