P: Very strange performance problem in develop module

[LRuser24]

I discovered a very strange performance problem in LR4 final (64 bit, Win7):

1. Load a RAW file into develop module, e.g. from a Canon 40D
2. Reset to adobe defaults
3. Set "Highlights" to a different value than zero, use e.g. -40
4. Change the exposure value. Refresh rate should be relatively fast.
5. Now turn *off* the entire "Detail" section.
6. Change the exposure value. Refresh rate drops dramatically!

The strange things are: a) The refresh rate does *not* drop if sharpening, luminance and color noise red. are all set to zero instead of turning of "Details". b) The refresh rate does *only* drop if the "highlights" or "shadows" sliders are set to something different than zero ("whites" and "blacks" do not matter!).

The effect seems to happen in all zoom stages, and seems to affect all other settings, too, e.g. clarity and saturation (and even "highlights" or "shadows" themselves).

Edit: There seems to be no similar effect in PV 2010 - using recovery and fill light while "Detail" is turned off does not affect performance.

[LRuser24]

This strange behaviour can still be seen in the 4.1 RC.

I don't want to complain about it (the problem itself is not so significant). However, I just wanted to "bump" this problem because it may be valuable information for the Adobe engineers who are currently working on optimizing LR4s performance (see the other thread concerning the controversial temporary deactivation of sharpening when moving sliders).

I mean - something could be potentially very wrong in the internal processing pipeline of ACR when switching *off* a processing component (sharpening + noise reduction) causes performance to become *worse* so dramatically - instead of becoming better, as one would normally expect.

[J453]

Hi, Lightroom QE team was able to repro and have logged a bug into our system. Thanks!

[Benjamin Warde]

This issue has been fixed in Lightroom 4.1, which is now available. To download the 4.1 update, go to the Help menu in Lightroom and choose "Check for Updates".

Thanks,
Ben