I always see the servo team constantly benchmarking things that are parallelize to make sure the parallelization is worthwhile. So if anything, I'd expect end-u

I always see the servo team constantly benchmarking things that are parallelize to make sure the parallelization is worthwhile. So if anything, I'd expect end-user latency to decrease substantially. I think the biggest improvements may come from experimenting with new asynchronous DOM APIs, which the browser can intelligently batch up for performance. Unfortunately, web developers will have to use these APIs for them to have any effect, and it seems to be a long way away right now for real world use. But it's part of what Servo will be helping to explore, as I understand it.