Hi - if I may add to this thread...
I have encountered a similar phenomenon. After perusing these forums for quite a bit, I guess I have the same problem. I have a new installation of P3Dv4.3 and have 40-50 fps when flying. On my last flight however, I had 4 events where the Airbus would bank more than 30° left or right or either climb or descend with more than 4000fpm from literally one second to another (I analysed the recorded data provided by fs-flight-control, a tool I use). The thing is, that two of these four events occurred over open seas - so no bigger scenery close by. There was also no AI traffic present (neither on the ground nor in the air). I do use AS16 and I suspect, that the weather injection is part of the problem.
>> Can someone confirm, that in straight and level flight it is enough for the FBW to behave like this, if the FPS drop below 18fps for up to 2 seconds (is that "smallish" enough?)
>> Also: has anybody made the experience that weather injections (esp. by AS16) cause this kind of fps drop? I have read here somewhere that there is a ton of data injected into the sim, but it isn't quite clear to me if that is a confirmed fact or an assumption.
>> Is anyone also using UT-Live and has experienced this behavior?
P3D 4.3 (new installation) on SSD