Photoshop hogging memory for decades

[JasonBatley]

Ever since I first started using PS it has hogged memory for no reason at all. Here it is sat hogging 15GB with one small file open. Yes I know I can set a limit to it but I want to let it use memory when it needs to, not grind my system to a halt while doing nothing - why has this been a problem for 2 decades?

[davescm]

It was designed that way for speed. Photoshop uses RAM, up to the maximum allocated, but does not hand it back to the operating system, otherwise it would be necessary to request it each time. The OS can get back the memory should it need it.
Never set the memory allocation in preferences to greater than 75% or you will start to see issues.
Dave

[JasonBatley]

What a ridiculous way of doing things - and totally illogical. No other program that I have ever used causes this problem. So it basically hogs all the memory to save a millisecond when loading a new file? Wonderful.

[D Fosse]

@JasonBatley 

You haven't considered the implications. Batch processing would be glacial to impossible.

[davescm]

'No other program that I have ever used causes this problem'

Raster editing shifts an incredible amount of data around. It is not about the RAM being required for loading a new file, it is about sufficient ram to carry out any operation that changes the image, curves, hue, blending, zooming, filters, layers , smart objects etc all need RAM. As D Fosse says, if you reduce the allocated RAM then Photoshop will swap with the scratch disk more often.

Dave

[JasonBatley]

Dave I am not bothered about it taking the memory when required, what does bother me is that it sits on it when not required.

[davescm]

As explained, reallocating to the operating system then re-requesting every time you carry out a function, e.g. scrolling, turning a layer on and off, adjusting a curve would slow the system down considerably. Then you would indeed be bothered and quickly complain that the tools had ground to a halt. That is why it was done this way by design.

Dave

[D Fosse]

@JasonBatley 

You can always make a case that the engineering team is simply incompetent, but for such a fundamental core function in the application architecture, not very likely. They had reasons for doing it this way. And those reason have been explained here in the forum, by engineers, and that's how Dave and I can tell you this with confidence.

I would suggest you accept how the software actually works, and find ways to work with it, rather than banging your head against it. That will save you time and energy that you can put into productive work.

[D Fosse]

First of all, never set Photoshop memory allocation to 100%! It will be taken, and then all your other applications and processes choke. It will slow everything down and eventually grind to a full halt.

The thing is, Photoshop will need a lot more memory than your installed RAM. That's why Photoshop uses a scratch disk, to write temporary working data to disk. That's Photoshop's main memory as you work. RAM acts more like a fast access cache.

In other words, it's much more important that you have enough, fast, scratch disk space, than the amount of memory you assign to Photoshop. Whatever you do assign, will be taken up very quickly, and it won't be released again until you close Photoshop. It will be recycled and reused.

With slightly less RAM, Photoshop will just hit the scratch disk slightly more often. That used to be a rather big deal back when hard drives were slow spinning disks, with a read/write head that could only be in one place at a time. Today, with ultra-fast NVMe drives, the amount of RAM is a lot less important. For all practical purposes, the scratch disk will be as fast.

In short, dial it down to 70% at most. Those 70% will be saturated quickly, and that is not a problem. Just leave enough for the rest of your system.

Even the ACR plugin runs outside Photoshop's address space, and needs its own memory separate from Photoshop.

[D Fosse]

Cross posting, saying the same thing, short and long version 🙂