That's the accounting for a running process when using top under linux (and probably on other systems such as BSD, Solaris, Mac OS). I have two CPU : it's just one dual core CPU I have, but this is logically equivalent to having two CPU.
Amazingly the same program displays a sum up line of CPU use (user-space programs, kernel, idle, blocked by I/O..) in the up to 100% format. ugh.. but it's fun to read that some program is using over 100% meaning there's some multi-threading happening for good.
Now, to say something useful in my post : I ended up blocking ads with Ad Block Plus, but around the beginning of this year a new blocking extension got popular, uBlock.
It is open source, simple of use and hardly uses any CPU or RAM. So it does make the browser quite lighter and it also blocks some of the user tracking stuff not just ads.
I had a problem of firefox taking a long time to close, that went away.
These days blocking flash with Flashblock is troublesome, though. So I uninstalled it.
