Sitting here with 4.4 RC, processing D800 files. This is the i5-750 (quad) machine, 16 GB, all spinning drives, that I've had some problems with up to now. Nothing dramatic, but those quarter-second/half-second delays that can be pretty annoying when you have lots of files to go through.
Now it breezes through, distinctly better than 4.3. In short, this is good. May it stay that way.
But, interestingly, 4.3 RC was just as good - until the final came and it was back to the trenches again. I'll keep a very sharp eye on the final 4.4.