This more a negligence complaint than a bug report.
The Problem:
In compressed files (PSB, or TIF and PSD with any compression options turned on) the bottleneck when opening and saving a file is your processor's single-threaded performance. You will never get anywhere near the throughput of even a slow hard drive from 10 years ago.
I've read lore that there are computer science reasons that this kind of compression can't be multithreaded. But I doubt it's true. For one, a friend who's a developer and imaging engineer doesn't believe it. For another, I've run tests that show Photoshop can't even save two entirely separate files simultaneously. If you have multiple images open and hit save one after the other, they will still save one-at-a-time. We know this can be multithreaded. Adobe's own lightroom will make each image its own thread and distribute to all the processor cores available when importing or exporting.
Evidence:
I made multiple copies of a 1GB image. This was from a 36MP camera, and had several image layers, adjustment layers, and channels.
I tested on a Mac Studio with M2 Max processor, 64GB ram. I repeated the test with the internal 2TB drive (which tests to over 6GB/S throughput with large files, and an external 8TB drive (Micron enterprise u.2 nvme drive in a thunderbolt enclosure; tests to over 3TB/S throughput with large files).
I also made edits to each file and saved them all simultaneously. I watched activity monitor to see thread activity and throughput.
For some reason the external drive saved the files faster than the internal, despite my benchmarks, so those are the Save results I'm reporting:
AmorphousDiskmark 1 1GB: 3020 MB/s
No compression: 388 MB/s
TIF; LZW / RLE: 51.7 MB/s
TIF; ZIP / ZIP: 3.16 MB/s
In summary:
- With no compression we get just better than an order of magnitude slower than the drive's maximum speed;
- With LZW we get a little better than 2 orders of magnitude slower;
- With ZIP/Zip we get barely more than 3 orders of magnitude slower.
- We don't even get parallelsim when saving multiple files at once. They just line up one after the other, like sad cows limping into a slaughterhouse.
Conclusion: Adobe, what are we paying you for every month? This isn't ok, and I don't understand why your customers let you get away with it year after year.
Many of us do not need pervasive AI and embarassing effects. We need you to fix the broken things that have been slowing us down since the 20th century. Computers are crazy fast now—if you don't sabbotage them.