Any idea how updates are so smooth?

I had started the update of Chrome from v14 to v15 in a terminal session and, without realizing, continued using Chrome 14 for browsing. After a while, I went back to the terminal and found that everything was done. I closed Chrome v14 and reopened to have Chrome v15 running without any grinding or churning or elevated CPU activity. Pretty neat.

And Chrome 15 seems to take ~1 MB less space. Perhaps, Google is following up with their intention to lose some bloat:
http://www.thechromesource.com/google-making-effort-to-reduce-bloat-in-chrome/

The reduction refers to the install and not post-install