After playing around with it for a few more minutes it seems that the rendering is very quick. Spawning a bunch of tabs might be a little bit slower then Firefox, but I would guess that this is because it has to spawn a new process for every new domain you open.
I'm running this on my work machine, which is a P4 3.2 GHz. I will be interested to see how it performs on my quad core system at home. It should perform a lot better since the system should automatically assign processes across the cores. Whereas Firefox's multi-processor support is very bad.