Running Lightroom on a Quad-Core Processor

I recently built a computer focused on digital photography. Probably some where near 80% of the time I spend on the home PC is using either Lightroom or Photoshop. Being the obsessive type, I did a lot of research to figure out the best configuration. Much to my surprise, there was little beyond what seemed to be uninformed opinion as to whether the best bet would be a dual or quad core processor.

Everyone agreed that Memory was more important, but given the price of memory these days, that wasn’t particularly useful advice. At $169 for 8GB 1066 DDR2, going for a major chunk of memory was a no-brainer. The story on Photoshop seemed to be fairly clear, there aren’t that many tasks in Photshop that take advantage of 4 cores. Besides, even on my 6 year old, 2.2 Ghz Pentium 4, Photoshop wasn’t the problem, Lightroom was. Frankly it was unusable. With my 40,000+ image library, even scrolling through the grid view would cause the machine to shutter and shake. The new adjustment brush in 2.0 wasn’t workable–but the time the adjustments showed up on screen, I’d have already messed up the adjustment because I couldn’t tell what it was doing.

In the end I went with my gut. It seemed that a lot of the things you do in Lightroom, whether on ingest, export or printing, are trivially threadable as they are operating on multiple images at the same time. Plus, just before I finalized the order Intel dropped the price on their Q9550 by about $200.

Here is the configuration for my build:

CPU Q9550 Quad-Core overclocked to 3.4 Ghz
Motherboard Asus P5E Delux
Memory G.Skill 2x2GB (time two)
PowerColor HD4850
Case Cooler Master Cosmos S (seems that this keeps the drives cooler than the regular Cosmos)
Cooling Thermalright Ultra-120 extreme
Cooling Fan Scythe S-Flex SFF21F*
Powersupply PC Power Silencer 750 Quad 750W
Harddrives–System Seagate 7200.11 750MB
Harddrives–PS Scratch WD Caviar 160GB
Hardrives–Data Seagate 7200.11 1TB
Optical Drives Samsung SHS203B
OS Vista 64-Bit Premium SP1

Total cost for the system was about $1700 on Newegg.

So how did it work? I’ve done a bunch of different Lightroom task and captured the task manager data to show what is going on.

Ingesting Images

My hypothisis here was that LR would be mostly disk bound on this task and the quad-core would be of little use. I was surprised to see even during the initial stage all the cores were being used at about the 40% rate. During the rendering standard size previews stage, the quad-cores were being used at an even higher level. Here is the task manager during the initial import:

And here is the task manager during the rendering of the standard previews:

Develop Stage

Where before I would have to wait on each and every move of a slider, the response time is instantaneous. Though again, I really didn’t expect the quad-cores to be highly stressed, there was more usage than I expected. Here is the task manager output for a simple increase in fill light:

Using the adjustment brush also held a surprise as at least 3 of the cores were put to work. Note that this was with an auto mask. Here is the task manager:

Output Processing

Here was were I expected to get a fairly major benefit from the Quad-Core and it didn’t disappoint. Here is a typical example using the Print module to output 8 pictures 2up 6×9 on an A3 sheet.

Perhaps more surprisingly, even outputing a single 6×9 on letter sized paper drove usage of all 4 cores:

Conclusion

I’m happy with my choice. I realize to be scientific about this, I’d have disabled two of the cores and done timing comparisons, but even looking at things that way you would need to decide what parts of the workflow were more important to you. For me, the quad-core does reasonbly well at being utilzed for parts of the workflow that don’t take that much time, and makes a major difference in the parts of the workflow that can take a lot of time–in particular any output processing.

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~ by aphotogeek on October 4, 2008.