RokBooster can dramatically reduce the number of HTTP calls a browser has to make, and sending those compressed files GZipped means your pages will load faster with less load on your server.
— Customizable cache timeout
— Background rendering, so initial file processing won't slow your users down
But sadly, after I activated it, Pingdom and Google Page Speed could not reach the website.
And when I refreshed, all the css got jacked up .
To my understanding, there can be never a complete 100% perfect compression app for Joomla.
This issue is typically associated with server permissions. Therefore, in version 1.1.5, we added the ability to change the permissions of the compressed files from 755/644 to 775/664, which are necessary for some servers. Therefore, I suggest that you try that in RokBooster's Advanced Options, clear your cache, refresh and see if it works.
Feel free to contact us at http://www.rockettheme.com/contact-us and if you have posted in our forum, please provide a link to your post in email. We'll be happy to look into it.
The only issue I had was with Virtuemart pages not displaying, but a quick search in their forums provided me with the answer.