Well this is the first time that it has happened to me. I’ve had the option file downloaded for a few weeks and no such issues before today. So the only thing I could put it down to, was the camera. Especially as it instantly corrected itself once I changed it back. Really reluctant to ever try changing the camera again from now on, haha!
I did a database rebuild. And it's back to silky smooth. My heart leapt for joy (I'd had that sinking dread feeling the last few days when you know your favourite toy is broken...)
Might b worth trying it...
A while ago someone mentioned stuttering and frame rate drops. I've noticed turning of all automotion and judder settings removes this problem.