I'm running Lightroom 2.6 on Windows XP and it runs painfully slow. Just navigating from one image to the next takes a few seconds.
What can I do to speed it up?
Something that hasn't been mentioned yet: in 'Catalog Settings' turn off 'Automatically write changes into XMP'. This will prevent LR from automatically dumping its catalog metadata, keywords, rating, labels and develop settings back to your photo files. By doing so you will reduce the number of disk operations performed by LR. You can still write your metadata back manually, as I describe in this other question.
I have 8GB of RAM and I process 21MP RAW files out of a Canon 5DMII. Increasing disk performance is how I made it run faster. I replaced a pair of fairly zippy Hitachi SATA 15,000 RPM drives by a pair of 160GB Intel X25G2 SSD. Be careful with your choice of SSD drives, they are not born equal. Most of them read really fast, but many are slow on write. Pair your SSD with a modern operating system like Windows 7, one that supports the TRIM command.
What should you put on a SSD and what should you leave on a standard drive? Opinions differ, but here is what I would recommend:
What is the Camera RAW Cache? Quoting Jeff Schewe via Luminous Landscape Forum
You can change the default location of your catalog, previews and Camera RAW Cache from the Preferences and group them on the same SSD. I would definitely recommend increasing the size of your ACR Cache, if you can afford it.
RAW files are big. You don't need to have all of them on a SSD, but what about the past 6 months worth of photos? Move older photos back to a standard drive every month or so (do it from LR of course).
Do you need to put LR or the whole Operating System on a SSD? If you can, sure, it will start faster and feel a bit more responsive, but I don't think it's critical. If you don't have a lot of RAM though, try to put your page file and TEMP directories on the SSD.
Should you go RAID0? I really recommend against it, unless you have really strong backup habits and monitor your RAID controller regularly. Remember, RAID0 uses 2 drives: if one dies, you lose the data on both. Don't risk it. I personally like RAID1 a lot for this very reason and from past experience.
Finally, you will "feel" LR run faster if you let it generate your 1:1 photo previews during import. I usually do something else during import anyway, run some errands or whatnot. In any case LR has to generate your 1:1 previews sooner or later when you go to the Develop module, right? So you might as well let this happen during import.
Upgrading to Lightroom 3.2 is cheap and easy. You'll find version 3 a lot more responsive than 2.6, and version 3.2 even more so. In most situations where Lightroom 2 makes you wait, Lightroom 3 will do its processing in the background, so you can continue to interact with the program.
You didn't say what hardware you're running, but if you're using Windows XP, it's probably an older system. Lightroom really taxes PC hardware. Getting the fastest PC you can afford is definitely a good idea. I'd recommend a 64-bit system with lots of RAM and an SSD drive. If you can't afford an SSD big enough to store your images, use an SSD for the operating system and your Lightroom catalogs, and a normal hard disk to store your RAW files.
Lightroom doesn't benefit from multi-core CPUs as much as I'd like. If you tend to have Lightroom run multiple background tasks (import, export, render previews) as the same time, your computer will stay more responsive with a quad core CPU. If you don't run multiple background tasks, then a dual core may be a better choice. For the same money, the individual cores on a dual core CPU are faster than those on a quad core.
Lightroom does not make use of GPU acceleration at all. So don't spend money on a graphics card unless you need it for other purposes.
Without knowing the amount of RAM or processor speed, it's hard to make specific recommendations, but Lightroom will perform significantly better with more RAM and a faster processor.
It also doesn't hurt to occasionally optimize the Lightroom catalog, which helps increase the efficiency of operations. On a PC it's under Edit->Catalog Settings, on a Mac It's under Lightroom->Catalog Settings. Click the "Relaunch and Optimize" button. Lightroom will do just that. It can take a while depending on the size of your catalog.
Don't let the catalogue grow too large.
Separating your pictures into several catalogues can bring a lot of speed.
For me the main waiting point is waiting for Lightroom to render the 1:1 previews - if I let Lightroom render those on import I can usually work faster.
Of course putting the catalogue on a fast hard disk (SSD) helps, too.
Upgrade. LR 3 is a fair amount faster for me. I also have found that RAM seems to matter more than raw processor speed, at least for me.
I'm not sure how well Lightroom performs when your catalog grows too large. I'd recommend improving general system performance by addressing the following areas:
In terms of Lightroom itself, I can only suggest creating smaller catalogs.