I think this is a good opportunity for me to get the Steam edition. Dovetail games did make a number of changes to the FSX engine code to improve performance. From the videos that I have seen, textures seem to load a little faster, sim play seems a little smoother and the dreaded OOM error is greatly reduced. The downside has been that you must be on the internet to fly the FSX Steam Edition (soon to be fixed) and some add-ons are not compatible. As the Steam Edition has become more popular, most add-on developers have made their products Steam compatible. No, it's not a 64-bit version of FSX, but neither is Prepar3D, but the Steam Edition is a lot less expensive than P3D and does not require DX11.