GPU USELESS For Lightroom Classic!

Started 3 months ago | Discussions thread
Simon Garrett Veteran Member • Posts: 6,875
Re: GPU USELESS For Lightroom Classic!

skyglider wrote:

Simon Garrett wrote:

The 3900X is not hugely faster than the i7-6700 at single-core speed, but it has 24 processors as against the i7-6700's 8, and so has much greater all-core speed.

I've made the same upgrade (in my case i7-6700K, slightly over-clocked) to 3900X, and here are the CPU-ID benchmarks: first figure is single-core speed, second is all-core:

i7-6700: 474, 2377

i7-6700K: 483, 2555

3900X: 532, 8201

Processor clock speeds have not risen greatly since the i7-6700, but current processors have many more cores. Lightroom does not seem to use anything like the 24 processors on my machine, but uses around half of them when exporting or building previews.


I quite agree with you: a powerful graphics card is wasted on Lightroom.

Better, I think, to spend money on a fast M.2 NVMe SSD for C drive, raw cache, catalog and previews. That can all be the same drive if it's big enough.

Hi Simon,

Since you upgraded from an i7-6700 CPU to the AMD 3900X, just wanted to get your opinion.

I'm running an i7-6700 CPU and I have never experienced any slowdown when editing in Lightroom5, Photoshop7, or SonyMovieStudioPlatinum12 video editing.

Where is the additional speed of an upgraded CPU evident? I'm not saying that you made any such claim but I respect your expertise so would like your viewpoint based on your experience.

(in case it's needed, additional specs for my system are: 16GB DDR4 2133MHz ram, Samsung 860 EVO, 500GB SSD system C drive, 2TB 7200rpm hard drive for data storage.)


On my 3900X machine, LR is faster at building previews, and thus scrolling through the library with images I haven't looked at recently, and exporting is faster.  I suspect that the speed increase in mainly with tasks that use multiple cores (12 against the i7-6700's 4), and faster throughput to/from the processor, faster memory and faster SSDs.

Single core clock speed of the 3900X is only 12-14% faster than the i7-6700 (10-12% faster than the i7-6700K) but multi-core speed (all cores active) is 350% faster.  LR uses multiple cores mainly for export and preview-building.

Clearly (in my build) disk-intensive tasks will benefit from the faster SSD.  The SSD I'm now using for LR catalog and previews is 7 times faster than the one I was using before, and 2 times the speed of the one I was using for raw cache.

LR is also faster and with fewer pauses generally, but what aspect of the new build contributes to that I'm not sure.

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