I've also encountered this issue. My setup isn't top-tier, but it's perfectly capable of a smooth flight. I was very happy with my flights before the recent updates, but with each new version, the performance has gotten worse. The latest version of the A350 has the lowest frame rate I've ever experienced. I even doubt if it can complete a full flight (at this frame rate, I'd probably have to rely on autoland). A good example of this is time acceleration. Before, I had no problem using 4x acceleration, but in the latest version, as soon as I enable 4x acceleration, the plane starts to convulse (I hope my passengers don't mind the sudden altitude drop (￣_,￣ )). Even at 2x speed, you can clearly feel the abnormal swaying of the plane, which never happened before. I really like the A350, and I hope iniBuilds can find and fix these issues. I look forward to seeing performance improvements in the next update (returning to previous levels would be great). Until then, I'll have to fly something else, as I really can't experience flying with the current frame rates (* ￣︿￣).
