Kathoum is a hot place. After 9 in the morning temperatures sore well about 37 degrees, and performance now degrades `exponentially`. Your ten knot head wind also usually goes away and now comes the fighting with ops to offload A LOT. Even if you insist and convince you cannot personally weigh the cargo or pax for that matter, so you have to trust your loadsheet...feel how the plane flies and check the cruise performance. But this is after take off..
Been fighting myself, and left..