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Fried Green Pixel
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Why is Lightroom 2.4 Thumbnail Rendering SLOOOOOOOOW...?

Jul 14, 2009 4:16 PM

For some reason Lightroom 2.4 is taking an enormous amount of time to render thumbnail previews and in spite of having my thumbnail cache set to 50 GB, it still re-renders the thumbnails every single time I use the scroll bar.


Every other aspect of Lightroom performs just fine on my machine.  But the library is so slow that it is unusable.  Every time I touch the scroll bar I can see a somewhat darker preview of the thumbnails and then as soon as I stop scrolling, the CPU shoots up to 100% utilization and I watch as the thumbnails brighten and adjust one by one.  30 to 45 seconds later I can click on the thumbnails and navigate around just fine.  Performance is great in fact until I touch the scroll bar again.


The basic question is this.  Why does Lightroom refuse to cache my thumbnails?  And why does it take soooo long to render them when Vista's explorer can render hundreds of thumbnails off even a flash card in seconds?  Even if thumbnail rendering was slow it would be fine if Lightroom would only cache them for me so it doesn't have to redo it every time I scroll back and forth.  Shouldn't there be an option to render thumbnails on import as well as 1:1 previews?


I am running Vista 64 bit with 4GB of RAM with a Gforce 7600GT graphics card.  My library has about 18,000 images in it.  But I've also tried with a brand new small catalog.  I'm shooting and processing Nikon D300 RAW files.


I've done all the standard performance tweaks that everyone talks about:


1.  I render 1:1 previews and never expire them.

2.  I have tried all the various nvidia card tweaks.

3.  I've updated to the latest and greatest nvidia drivers.

4.  I have my catalog on a separate drive from my images, and my thumbnail cache on yet a 3rd drive.

5.  My machine has plenty of RAM, and in fact Lightroom is only using 1.5GB leaving me with well over 1GB remaining.

6.  My machine is not swapping at all.


I've been reading and reading for the past 24 hours about this issue but have yet to come up with an answer to it.  I did find this old thread from over a year ago that describes the EXACT same problem I am experiencing except his problem was with version 2.3:


Does anyone have ANY idea what can be causing this?  As is, I can't use Lightroom under these conditions.



  • Currently Being Moderated
    Jul 14, 2009 4:59 PM   in reply to Fried Green Pixel

    Quote "4. I have my catalog on a seperate drive from my images, and my thumbnail cache on yet a third drive."


    Could you expand on this. It would be best, provided there is sufficient room, to have the catalog, previews and the cache on main HDD with the program file.

    It would be ok to have your images on another drive preferably an internal HDD but an exernal drive is also ok.


    Do not consider a partitioned  drive to be another drive its still one HDD only seperating files so there is no performance benefit.


    Better to keep the external drives for  backup .

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  • Currently Being Moderated
    Jul 14, 2009 6:50 PM   in reply to Fried Green Pixel

    What you have done make sense, but it was not specific in your original post. What I was suggesting was if you had two internal drives. I just wanted to make the point that having the catalog, previews and cache on external drives would not be the way to maximize performance. I have no idea why you are experiencing the slow performance.


    Just one other point the Library module uses the previews but when you are in Develop module the raw files are used to render the display. Its more efficient to use the Library to browse.

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  • Currently Being Moderated
    Jul 14, 2009 7:24 PM   in reply to Fried Green Pixel

    Fried (or Mr./Ms. Pixel),


    For whatever reason, that was the way Lightroom was designed. When you bring a thumbnail on screen in grid view or on the film strip, Lightroom applies the develop settings and creates the thumbnail badges. The process isn't over until the "..." goes away.  With Lr 2.x it takes longer the first time it does this for each screen full of thumbnails, about 30 seconds on my zippy Core2 Quad. Thereafter it takes much less time for the "..." to disappear for those thumbnails, 1-2 seconds for me.


    Something I haven't noticed before Lr 2.4 is that now and the "..." will freeze for a few thumbnails and won't go away until you scroll them off screen and then back on.


    This has been discussed in innumerable threads from Lightroom's beginning.

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  • Currently Being Moderated
    Jul 15, 2009 3:32 PM   in reply to Fried Green Pixel

    It sounds like you are on the right track. Sometimes the Previews folder becomes corrupt. What I might suggest is changing the name of either the .lrcat or the Previews folder' either one will force build a new Previews for the whole thing. If, after checking out a couple of folders in the old .lrcat but new Previews, things aren't better, you can just change the name back, and you'll be accessing the "old" Previews folder. But I bet you'll see an improvement on everything.

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  • Currently Being Moderated
    Jul 15, 2009 5:10 PM   in reply to Fried Green Pixel

    No, I wouldn't say it's common, but as usually folks post here to solve a problem, it - slow performance- shows up every few days- but it isn't always a corrupt Previews file, to be sure. I wouldn't expect it to happen again.

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  • Currently Being Moderated
    Jul 16, 2009 2:55 PM   in reply to Fried Green Pixel

    Glad it's fixed. I am pretty sure it was the part of the new catalog that brought you a new Previews folder that fixed it, but your method covers that base nicely, with a bit more time and work.

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