Drag increase and subsequent performance decrease.....
Whatever your performance limited TOW is on the day for your flight no matter what method your company uses you have to then reduce that by 10,080 kg.
In ours we simply input the CDL code into our ACARS TO PERF calculations and it takes care of the calculations/corrections/penalties and gives me the figures.
PERF Limited TOW, FLEX, CONFIG, VMCG, V1 VR V2 etc etc