Remove W3 Total Cache debug test from feed

Hi,
I use W3 TC for Performance enhancing on my blog and it works fine except for one thing.
For my feed, it outputs some logs which makes the xml file invalid.
Here you will see
At the end of http://www.batterievoiturepro.com/feed/atom/ after the closing feed xml node you have:

<!-- Performance optimized by W3 Total Cache. Learn more: http://www.w3-edge.com/wordpress-plugins/

Minified using disk
Page Caching using disk: enhanced

 Served from: www.batterievoiturepro.com @ 2013-11-06 16:23:22 by W3 Total Cache -->

My feed can’t be parsed by third parties because of this problem.
Please in which config/settings can I disable that debug text?
Nicolas.

http://wordpress.org/plugins/w3-total-cache/