Been running it in FSX boxed for several months, all seems ok, no loss of FPS, I have an old version of FSX with REX, UTX, GEX & DX10 Fixer.....watching traffic coming and going today all good even on 100% traffic......originally was testing in P3D4 but I thought FSX was being neglected so I opted for that.....stiil Early Access so anyone tempted bare in mind it's not finished but there are discounts......