I’ve already blogged about RAM vs CPU in an earlier post see: Ram vs. CPU. Adobe claims that Lightroom supports multiple CPUs.

This leads to the question, what kind of computer to get. And let’s not start the Mac vs Windows wars. By the way, this applies to both Mac and Windows. Should you get a Quad core CPU, an i3 CPU, an i5 CPU or even an i7 CPU? And what about the RAM?

First I must explain my setup and how empirical is my testing.

  1. I run an Intel i7 core with 4 embedded CPUs with hyper-threading. As far as the operating system is concerned, it looks like 8 CPUs. Think about it, around a thousand dollars, and a hundred thousand times more computing power than what NASA used to send Apollo 11 to the moon!
  2. I run Windows in a virtual partition with Vmware Workstation. So if anything happens, it will not affect the rest of the computer. Windows doesn’t know anything about the real computer. The other benefit is that I can change the configuration from 1 CPU to 2 CPUs or even 4 CPUs. I can also change the amount the memory allocated to the computer.

So I tested Lightroom with 2 CPUs and 3 Gb RAM on Windows 7 Professional, vs Lightroom with 4 CPUs and 3 Gb RAM on Windows 7 Professional.

Remember the task manager from: Ram vs. CPU

Task Manager: RAM & CPU Usage

Task Manager: RAM & CPU Usage

When I import, only 1 CPU is running 100%, the other CPUs are idling and doing almost nothing.

  1. Yes, Lightroom supports multiple CPUs.
  2. No, Lightroom is not a multi-threaded application. This means that Lightroom cannot spread a task between multiple thread or multiple CPUs.
  3. 1 Lightroom task = 1 CPU, 2 Lightroom tasks = 2 CPUs. This means that if you want to do a huge export, you should split the export into 2 or 3 smaller exports and they will be done at the same time.
  4. When it comes to Lightroom, you are better off buying the fastest CPU clockwise instead of the bigger CPU with more cores. So an Intel Core i5 CPU running at 3.06Ghz will be faster for Lightroom than an Intel Quad core at 2.66Ghz.
  5. Memory: Lightroom is very efficient, it uses the SQLite database and what’s on your screen needs to be memory resident. So my 13,000 images only uses 1.6 Gig of RAM on Windows 7 with Windows 7 gobbling over 800Mb of RAM.

Speaking to my daughter, she’s a Mac fanatic, she has found similar results.

Update for Lightroom 6 / Lightroom CC

Now Lightroom uses the GPU! What’s a GPU you ask? It’s a Graphics Processing Unit, it’s located in the video card and it’s fast, extremely fast. It displays things on the screen between 20 to 100 times faster.

Lightroom is using it for its recalculations.

You will need a good video card that cost between $200 to $1,000 (Canadian). It will speed up mostly the development module. The library will be faster when displaying an existing already build preview.

The disk operations are not any faster than before. These can be improved with SSD drives.