Lightroom 4.2 very poor CPU usage

Question

Lightroom 4.2 seems reasonably fast when I work with it, whether it's browsing photos or adjusting sliders, although it takes several seconds to go into develop mode after launching it for the first time.
But now I'm exporting 1498 photos that are 5184 by 3456 and it's taking quite a while, I would say about an hour or more. This is on a brand new system I just assembled consisting of an i7 3930k with 32 GB of RAM that flies with every other program. While exporting this batch I opened Task Manager and I noticed that CPU usage never goes to 100%, not even close. There are peaks of 50%, but on average it must be in the 20s:
This is very disappointing on a CPU that has 6 physical cores and 12 logical cores with hyperthreading at 3.2 with turbo at 3.8 Ghz. The batch is exporting these photos from one SATA 6 drive to another SATA 6 drive, and the HD LED barely lights up, so I know the hard drives are not the bottleneck. So I'm wondering, is Lightroom 4.2 really that bad when it comes to taking advantage of the CPU cores? Is there anything I can do to make it use the CPU more?
Thanks,
Sebastian

Answer 1

Victoria Bampton wrote:
Some people are finding that turning off hyperthreading is helping, so I'd be interested to know if that makes a difference for you. 
I would also split the export into 2 or 3 exports, which can run concurrently, which should max out your CPU.  They don't max it out by default in order to let you carry on working while the export runs in the background.
I would prefer not to turn off hyperthreading, since part of the reason I spent $1300 in a system upgrade was to get that feature and it's not practical. Even if it worked, I would have to reboot every time I need to do a long export, go into the BIOS, turn off HT, do the export, reboot, turn it back on. Too much trouble.
As for running parallel exports, it doesn't really help much. I tried cutting this export roughly in half and export at the same time. Here you can see the result:
At times it went up to 60% or so, but the gain in time is negligible. I ran the two exports more or less at the same time, the second one several seconds later because I had to select the rest of the photos, open the export dialog, click OK and then wait for the "Prepare for export" progress dialog to finish, after which it started exporting. So that export took 31 mins. And this is because I went into the Asus software that comes with the motherboard and set it to do an automatic overclock, which took quite a while but it sped up the system considerably. Before doing that it was taking close to an hour.
After that, I shift deleted all the exported files, went into Lightroom, selected all the pictures in the folder and exported using exactly the same settings, jpeg, convert to sRGB, no resize and limit of 7000kb. So the gain from doing a parallel export is only 3 minutes. Evidently, Lightroom is not well designed to take advantage of all the hardware at its disposal, even if it is a superb photo processing program.