Safe to use site performance plugins such as jbetolo?

My sites frontpage is very slow right now so I want to try out a site performance plugin. And my question is if it's going to work with Gavick templates? Because I have heard that for some people the template breaks when the plugin merge css and js files. That's why I ask you guys before I install it on a site with one of your templates (eSport). If you think there is a chance of the template breaking do you have another option? Because the frontpage loads in ~6 secs at the moment and that is not ok.

One of the plugins I have in mind is jbetolo (http://extensions.joomla.org/extensions ... ance/11545)
My site: http://goo.gl/hyUzk

Please check my performance report: http://gtmetrix.com/reports/goo.gl/nDp6hWLs

Please, I don't want to break anything in my template. So is it safe to use this tool?