Do you like Google's Favicon from 2012? That blue one with little contrast? No?
Then go old-school and use the 1998 one which has some colors in it.
Looking for the colorful icon from 2009 instead?
Here you go: Google Favicon 2009
For Google Chrome:
Google Favicon 1998 - direct download
Google Favicon 2009 - direct download
By someone else: G Favicon Fixer - chrome store
This add-on was made to be small, fast and efficient, it uses as few resources as possible.
This is why every icon has it's own version (and small icon :P). If you want to change other sites icons as well, see:
Greasemonkey (when you use it anyway)
or any add-on dedicated to that job...