Hi,
<Before optimising catalog>
I've tried using the upright tool and it's as snappy as ever. I've also tried manual perspective transformations, and they seem to be just as fast as they were before the upgrade to LR5.5.
I've also tried a handful of other operations (Vignetting, Post Crop Vignetting, Tone Curve Adjustment, Radial Filter), and they all respond at a decent pace. So currently, yes it's just cropping/rotating that are moving slowly.
<After optimising catalog>
I can't be sure whether I'm imagining it or not, but crop/rotate do seem to be a little smoother/faster. I was getting the "rainbow wheel" previously, and I'm not getting that now - there's just a brief pause while the image appears to re-render, and then we're underway again.
Again I might be imagining it, but it seems as though the drag/delay is greater when I'm cropping down significantly - slight downsizing of images doesn't seem to result in as much of a delay as massive downsizing by cropping.
I'll carry on like this and see whether there's a sustained improvement.
Many thanks for your help,
Vineet