Photoshop 2025 (26,3 release) - Saving PSD files takes forever

Machine: MacStudio M1 Ultra maximum specs.

By @nicholasc88636338

Yeah, if you watch macOS Activity Monitor, CPU tab, during a large Photoshop save operation, you’ll probably find that only one or two of the 20 CPU cores are being used. This is one of those examples where faster single-core performance makes more of a performance difference than adding more cores. Unfortunately, this negates the main advantage of the Ultra line of Apple Silicon: Ultra has the most cores, but all those cores don’t help much with Photoshop save times.

I think I’ve read that there are some aspects of Save operations that must be done in a specific order, so that it isn’t practical to fully parallelize it across all cores. But, last time I checked there were other photo editors that can save faster, so there is definitely room for Photoshop to improve this.

This is exactly why I've always turned off PSD/PSB compression.

I'm sure the compression algorithms could be improved, but as of now, they are what they are, and the open/save times you report are normal (depending on layers). These algorithms are old, and my guess is that they probably weren't written with current multi-GB file sizes in mind. On smaller files it doesn't matter, then it's pretty much instant either way.

But as for file sizes in general, I usually say that if you worry about that, you're in the wrong business. These file sizes will fill up your disks very quickly anyway, whether you compress or not, and the important thing you should concentrate on, is having a strategy for extending your storage space when it runs out. If you do, file size stops being a worry.