Hey, thanks for the quick support concerning the Stats question. Now I installed the plugin and it seems like it works pretty good and accelerates the website pretty much.
In the admin dashboard of the plugin I still get the message
"Warning! Garbage collection is not scheduled!
Garbage collection by this plugin clears out expired and old cached pages on a regular basis. Use this form to enable it. "
...but when clicking "this form", there's quite no option to choose from to be able to enable or disable that "garbage collection".