Denoise speed is the reverse of what I expected...

This came up because I need to do a presentation on some of the new tools in a week, and wanted to make sure the laptop was up to the challenge of doing Denoise and Gen Fill and Gen Expand and so on.

I found an old discussion from April where the answer kept being "get a faster CPU".  In my case, the faster CPU takes longer, and neither computer is even using the cpu for Denoise.

Desktop is i9-12900, 64GB, NVidia 4060 Ti 8GB, laptop is a 4-year old Dell 7740 with an i9-9880, 64GB, and a Radeon RTX 3000 6GB.  Both systems are Windows 11 Pro running 23H2.  Both systems have a 25GB cache and everything is living on NVMe SSDs on both systems.

Same image on both systems, in the same LR catalog (copied the whole catalog from desktop to laptop.)  Image is from an Alpha 1 in crop sensor mode, so it's about 20 megapixels.  Small.

I ran LR Denoise on the image on the desktop.  It consistently takes 1:53 +/- about 2 seconds - close to 2 minutes.

I ran LR Denoise on the image on the laptop.  It consistently takes 15 seconds +/- about 2 seconds.

The results from both look the same and while processing both systems ACT the same.  On the desktop the GPU goes to 94-98% busy for the entire time and the CPU sits at around 3%.  On the laptop the GPU goes to 95-99% busy and the CPU sits at around 5-6% the entire time.

On the desktop I turned OFF the GPU, restarted and got a popup telling me things would faster if I turned the GPU on, and I pressed CANCEL!  Ran Denoise on the desktop and the GPU STILL went to 95-98% busy.

Everything else in Lightroom (and Photoshop) that I've tried that takes long enough to measure is considerably faster on the desktop - Generative fill doing the same thing on the same image is always 30-40% faster on the desktop.  LR Photo Merge is faster on the desktop.  LR Select Subject (mask) is 3.1 +/- .2 on the desktop with the GPU OFF, and 5.3 +/- .2 on the laptop.   With the GPU ON and Lightroom restarted, the Select Subject is about 1.4 seconds, so significantly faster, as is my pereception of most things when I do a gross comparison of desktop to laptop.

The one anomoly is Denoise speed.