Well there are a few things that can make it run better:
Put the game in in window mode,lower effects on the game,lower your resolution and shutdown any back up apps running.(btw you can drop your chromebooks resolution by clicking on settings and then clicking on display.There should be resolution option there, tho if its not there you have to upgrade some of your drivers :p(i think).Tho to be honest i have no idea how chromebook works so no promises :p).
Thats all for now tho :p(i hope).Tho a warning your game will probably have nokia graphics after that,so its like a double edged blade effect :p.