I am upgrading my computer and I could not find a definitive answer. although I made the decision ot go with an i7 processor, the i5 processor i was looking at offers the same performance more or less for over a hundred dollars less.
I have not read whether it does or not. I did however, open my Resource Monitor and view the 8 CPUs activity graphs while I was using LR to edit an image. All 8 CPUs were showing activity during the process.
>All 8 CPUs were showing >activity during the process.
Windows? Most apps including LR have no CPU affinity, so all CPU's tend to show activity even lightly used, as threads are scheduled wherever convenient. Run a single threaded program that does regular (but not intensive) IO which is CPU limited and you'll see all 8 averaging about 12% busy each. Or 4 CPU's 25% each. Or 16 CPU's 6% each.
One of the ways you can tell how multi-threaded a windows app is, if you can make it run hard for a while, is look at task manager's CPU time, run it for a fixed amount of clock time (let's say a minute), and see how much the CPU time changes. If it changes by 4 minutes, it averaged using 4 CPU's, which would be highly parallel. I think you'll find Lightroom is more around 1.5 or less.
The smaller that number the more it helps to have a fast CPU. The larger that number the more it helps to have more cores (and maybe Hyperthreading).
I used to have a heck of a time explaining to programmers and DBA's why their 64 core super machine was running a (single) nightly job slowly, doing little IO, using no memory, and showing about 1-2% CPU busy.
I've had very little luck really pinning down LR performance issues, but here is what I THINK is true:
- The fastest core you can get the fast it runs - More cores make a difference, but not as much as fast cores - Hyperthreading doesn't seem to help, and may hurt a bit
- Memory helps but not beyond about 4G or so. - SSD helps a lot, the more SSD drives the better - SSD doesn't make much difference for actual images, but for .. Catalogs .. cache (acr, preview)
It's a bit erratic and inconsistent when you try to time and test things, LR does so much caching and preview building that doing two runs exactly the same way of anything is tough. But the above is what I've found in a lot of use since 3.x.
Anne pretty much insisted I go with the i7, which is theoretically the superior CPU, because she knows I would be second guessing myself for a few weeks after the build. (she is SOOOO much smarter than I am)
I've never seen this site before (see link below), but the author makes common sense. I'm sure true geeks may be able to support their particular position on what makes LR slow and how to speed it up. But the article is a good discussion starting point. www.learn-to-lightroom.com/article/buying-a-lightroom-computer/ The article mentions four bottlenecks - networking, disk (rotational speed more than size), processor (number of cores, speed), memory (RAM amount and speed, swap file issues), graphics (negligible, as "LR doesn't use math processor on GPU" yet).
Windows' Task Manager and Apple's Activity Monitor may show the number of threads, but I do not think casual users have the experience and knowledge to map out events such as which threads are bogged down by which processes; which thread is doing what, when.