Haven't heard about it until now. I'll test it right away.
I have only seen joomlatworks booster, but as that is under commerscial licence, it's the last exit. Especially as BentoBox as someone already said is pretty fast by itself...
Edit: I have noticed that sometimes the sites doesn't show at all. It says ready in IE, but the screen is empty...then I have to reload and try again..is that something ?