Do you see any difference when not working from a smart collection e.g. if the source is a folder or ordinary collection?
the issue is the same in smart collections compared to ordinary collections.
I'Ve realized I've opened a thread on 2015.6.1 a while ago with the same issue.
Not sure, but it looks like it is an issue with the preset I've applied.
Do these photos have a lot of brushing or spot healing?
Do all presets have this slowness, or just some?
no brushing, no spot healing.
It looks like simple presets are faster than complex presets, but I did not figure out, which setting actually kills the computer.
Any preset (even simple ones) causes an unresponsiveness for at least 1 second.
I've renamed my complex preset names into simple one,s as I was wondering if it is the file name. It's not.
Here are the presets:
And here's a recording highlighting the performance issues with each preset.
Does it help?
I have the exact same problem. It started with 2015.7 and hasn't been addressed in subsequent updates. For me the problem seems specific to Sony ARW files. this issue, which is exactly as the video show, only occurs when I'm editing files from any Sony camera. I have both A7 and A6000 and it's the same on both. I also use a X-Pro 2 and this problem doesn't occur with those. I have tried converting to DNG, which makes no difference. I have tried GPU acceleration on and Off, which makes no difference, and I've tried a new catalogue with no other files. I have a 12 Core Mac Pro with 20GB ram, so it's not like it's an underpowered machine. It also occurs on my laptop, a MacBook pro retina, but it doesn't last as long and is not as frustrating.
Incidentally, I have not added any preset, other than at import, to set profiles etc, so I guess that is technically a preset?
This definitely occurred with 2015.7 because I noted it at the time, because it occurred when the smart preview feature was added.
Please Adobe take this seriously and look into addressing it. There have been several point releases since then and this is still broken. I'm sure it's not affecting everyone, but it's definitely affecting some people. For me, Lightroom is virtually unuseable with Sony files at the moment.
If there's any information you need to help address this I'll be happy to provide. This isn't a software configuration, but it may be specific to hardware, although the original poster's was significantly different from my setup.