After some time, i choose the A350 to perform a longhaul flight EDDF-VHHH. After around 9h of flighttime, i run through the fms, showing the PERF page, i went on DES and want to have a look about the speed constrains, clicked the button and this causes a WASM crash. Very disappointing for me, with 1h of flighttime left to HKG i had to alt-f4. This was a IVAO Tour leg, so this leg was flown in real time with no time compression. I will not take the A350 in the near future again until these WASM crashes are COMPLETLY deald with.