If you have this already in your functions.php, you are set to go.

No need to change anything...
About your site:
1 Uncached Templates | DEBUG Mode OFF | GZIP ON (level 5) | 0.09 : 0.08 : 0.20
You have one template, not cached, that means you perform one query extra because the template name is not part of the cache array.
Also, I would switch the GZIP to level 1, 5 will slow down your server, IMO.
Server load averages gives me the hint you are on a dedicated server, that means you are rich...