It also feels laggy to me. It's weird given the reports of all these other users. I am also using a 16GB Ram, Intel Iris MBP. There is a noticeable pause while switching tabs, and there is a very noticeable lag while typing (for example in this box). Pages do seem to render fast, but it feels very laggy in terms of user interaction.
Edit: The scrolling is also very laggy, which I forgot to mention, much more so than Chrome.
Edit: The scrolling is also very laggy, which I forgot to mention, much more so than Chrome.