Suggestions to optimize piwik.js - decrease page load time

I run Piwik on Ubuntu 10.04.3 with a Varnish Cache and APC Cache in front of the actual webserver. I find that the piwik script is usually the slowest component of my page loads. What can I do to optimize the script further and decrease page load times. I have attached a screenshot of a page load toast on my domain with Pingdom for analysis.

use the asynchronous tracking code or use something like headjs in your page (if you’re already loading javascript)