Variable memory usage by PS (Beta)

[cbtsam]

     Running PS (Beta) 25.0.0 on an iMac Retina 5K, 27-inch, 2017, 4.2  Quad Core Intel Core i7, Radeon Pro 580 8 GB, 32 GB 2400 MHz DDR4, running Ventura 13.5.1.

     Opening a 560 MB .PSD file, Activity Monitor shows PS taking up 2.3 GB of memory.  Later, after opening another file (simultaneously) and then closing it, Activity Monitor shows PS taking up over 30 GB of memory.  I'd like somebody to know about this variation; it doesn't seem proper to me, a user of very modest experiste.

[davescm]

It sounds normal.

A PSD file on disk is compressed so disk space and RAM use are not comparable. In addition, Photoshop does not hand back RAM to the OS only to request it again when you open the next file.  Photoshop will use your RAM up to the maximum that you specify in Preferences Performance. It is normally advisable to restrict that to around 75% of your maximum RAM. If you set it too high, you could have other issues on your system.

Dave

[cbtsam]

Thanks, Dave; an illuminating response.  I'll just have to quit the app
more frequently, to reset the RAM hogging and keep it lower.

Sam Yaffe

[Conrad_C]

Before you quit the app unnecessarily, do one thing.

Go into Activity Monitor, and in the Memory tab, look at Memory Pressure.

If it is constantly green and the graph shows it never stays high for very long, you do not have a memory problem, regardless of what the numbers say. If Memory Pressure is green, it means the total macOS memory management system — memory chips, compressed memory, and swap memory — are able to keep up with all performance demands. If Photoshop is using 30GB of memory but Memory Pressure is green, there is no problem.

The only time to worry is if Memory Pressure is high (orange or red) for extended periods of time. That is the only indication that there is not enough memory, or a memory leak/bloat.

Apple specifically removed the "free memory" readout from Activity Monitor because it is no longer useful under modern memory management, and too often misinterpreted. Because of the way compressed memory and swap memory dynamically interact with real memory, adding up numbers in Activity Monitor is not useful. Instead, Apple added the holistic Memory Pressure readout, and made it prominent.