> I wonder if there are any estimates on how close to the original performance they think they can get. Do they expect to reach parity by, say, 1.6 or will it always be slower?

I imagine that's just a side-effect of rewriting the entire compiler; I'd expect the next versions to improve on the speed.

Though in the meantime, if compilation time is an issue, you can always try gccgo. On my larger projects, it's slightly faster than gc 1.5. YMMV, obviously.