After Google Chrome OS was announced and with the promises or goal of making it fast and lightweight, I know it will someday be compared with some of the fastest and lightest Linux distributions that are currently available. So I’m thinking I may never be impressed with Chrome OS if it can't beat or at least be at par with any of these distros:

antiX
I once dubbed antiX as "The Fat-free Mepis" because it is indeed the lighter and faster version of SimplyMEPIS. It runs really quick even on my ancient laptop since it is designed to work on computers with as little as 64 MB RAM and Pentium II or equivalent AMD processors. antiX uses IceWM and Fluxbox as its window managers and it is loaded with handy software packages.

SliTaz
SliTaz is considered by many as the world’s smallest 'complete' desktop distro.

rest here