> Are multiple cores being used to draw a webpage?
Yes. There is coarse-grained parallelism (e.g. script, layout, painting can all happen simultaneously) and fine-grained parallelism (e.g. every render object is restyled and laid out concurrently).
> If so, do typical webpages need this level of performance for a satisfactory user experience?
It depends on the site, of course, but preliminary results show that multicore style recalc and layout result in large improvements in many areas that feel slow today. Examples are loading new items on "infinite-scroll" pages and CSS transitions that require layout (e.g. "top", "left", "margin-right"). In particular, Web developers frequently write animations that require layout, so large improvements there have the potential to benefit apps a lot.
Yes. There is coarse-grained parallelism (e.g. script, layout, painting can all happen simultaneously) and fine-grained parallelism (e.g. every render object is restyled and laid out concurrently).
> If so, do typical webpages need this level of performance for a satisfactory user experience?
It depends on the site, of course, but preliminary results show that multicore style recalc and layout result in large improvements in many areas that feel slow today. Examples are loading new items on "infinite-scroll" pages and CSS transitions that require layout (e.g. "top", "left", "margin-right"). In particular, Web developers frequently write animations that require layout, so large improvements there have the potential to benefit apps a lot.