At the moment flying from London to Cape Town. I have all the winds loaded before departure. After takeoff my EFOB was just unter 10t, and my expected landing time was 1712z, now after around 3/4 of the flight the EFOB did rise to 14.6t. According ot the simbrief planning, around 11.3t would have been expected. Where does this huge difference come from? The winds are spot on, as planned in the flight plan. Also the arrival time has now fallen back to 1752z. How is this possible to have a 40mins gap (no reroutes or detour) but having more fuel left at the end?