Flaperon777
What has de-rate got to do with the basics?
On the 744 a 100T difference in T/O wt can give you V1,VR and V2 numbers that are approx 25-30kts different. Using a ZFW of 230t, fuel 120t you should get roughly 150/160/170. Take off 100t and you will get 125/130/145 ish.
That to me is not insignificant.