At least on A320. It is like a scratch pad entry. When you get the load sheet and final figures you cannot set the THS or configuration as there is no hydraulics. So you may have to write it on paper or memorize it. Instead you enter it on PERF page and after start set them accordingly. It doesn't go into the system and will create no warning or reminder unlike Flex which enters into the system. It is different on A330/340/350 models.