We, and i suppose most airlines for that matter, do not use books with tables. Instead we use an EFB-tool that checks performance for given parameters and selects the lowest possible combination of derate and assumed temperature while using or discarding improved speeds. So the performance gets lowered until we just fulfill the legar requirements to clear a given obstacle situation and staying within take off distances given.
It is sometimes interesting what kind of obstacles are there to be considered even at pretty much flat fields and i wouldn't even call the area surrounding LFPG as flat. But i have to say we only use that field as alternate for our next door stop at LFPO.