9.10.23_Which spec of cpu helps PS and why?

[Gene27167201cqus]

Hey all, which spec of cpu helps PS and why?

Specifically, I wanted to know which parts of the CPU help

w high dpi 300-600ppi (20x28in canvas) + large brush size

For faster pixel by pixel rendering speed

when laying down brush strokes real time

(Which also seems to be in line with mixer brush speed)

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From the research Ive done so far,

There’s 4 main factors for cpu...

=

Processing speed/mhz,

core, thread,

—- mb of game cache

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P.S.

Im not asking about how to adjust the brush or PS settings to make the brush lag less.

Ive done thorough testing and I know that its the increasing of the ppi thats causing the issue and only when brush size is large as well.

Ram, brush settings, PS settings are all fine when ppi is lower along w canvas size so Im specifically asking for help regarding upgrading CPU hardware knowledge.

[Trevor.Dennis]

Clock speed is king with Photoshop, so a CPU that runs at 5Ghz with six cores (ten threads) will outperform a CPU thst runs at 4.5Ghz and has 20 cores.  You can get real world, app specific data from the Puget Systems site.

https://www.pugetsystems.com/all-articles/?filter=processors%2Cphotoshop

(Change the filters to see how other aspects affect Photoshop and what other apps you run).

We have a home brewed benchmark we use to compare our systems.

Open a 30,000 X 30,000 8 bit document

Select the brush and a fully hard 5000 pixel preset with spacing set to 1%

Touch down in one corner of the document, and Shift touch in the diagonally opposite corner and check the timing.

Note: if you open the Info Panel Options and check Timing you'll get an easy to see indication of how long the last function took.  It also helps to be precise if you have cross hair turned on in your brush cursor.

To give you some context, I am running 

i9-13900K at stock speed

64Gb RAM

RTX4080

Samsung 980 PRO 2TB boot

Samsung 980 PRO 2TB scratch (nearly empty)

My last system also had 64Gb memory and never maxed out Photoshop's allocated memory, but did create some very large Photoshop temp files on the scratch drive, so it's important to pay attention to scratch space and performance.

I hope this helps.

[D Fosse]

I would think this relies on the GPU as much as the CPU?

Generally, I don't think I have ever opened task manager with Photoshop running and seen particularly heavy CPU load (i7-11700). Mostly it seems to be sitting around waiting for all those data to be moved.

My work machine, where I'm typing this, is awaiting delivery of an RTX 4070, so I'll hold off tests for now.

[Gene27167201cqus]

@Trevor.Dennis 

Travor thank you so much! 
May i know if you have any thoughts on the important oce the amount of MB of cache or sometimes also referred to as MB of game cache the CPU has?

I read on a different forum a person saying higher cache means better performance in PS as well.
Heres the thread)
https://community.adobe.com/t5/photoshop-ecosystem-discussions/do-really-big-brushes-slow-down-photo...
"if your processor memory is big like 8 - 10 mb then it not take such time but if you have 2-4 mb then might be slow your work."

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Also when you said 
"My last system also had 64Gb memory and never maxed out Photoshop's allocated memory, but did create some very large Photoshop temp files on the scratch drive, so it's important to pay attention to scratch space and performance."

I was wondering about the correlation between RAM and scrath disk.
An artist I watch who paints with alot of layers in a similar resolution to what I mentioned in OP
But also has the same RAm as me at 32GB....

Never seems to have any bottlenecking issues yet I do when I notice my RAM heads to 80% (And what im saying is, he shoud also be doing his work at 80% ram capacity like me yet he doesnt bottleneck.

The only difference is that hes using a PCI SSD for saving and loading PSD (And potentially as his scratch disk too) and Im using a normal HDD as scratch disk.
He uses) Force Series Gen.4 PCIe MP600 500GB NVMe M.2 SSD

So im wondering if a SSD PCIe scratch disk can replace the need for higher ram
when working on high rez + high file size psds?

[D Fosse]

So im wondering if a SSD PCIe scratch disk can replace the need for higher ram
when working on high rez + high file size psds?

By @Gene27167201cqus

That is essentially correct. Think of the scratch disk as Photoshop's main memory, and RAM as a fast access cache.

With the new ultra-fast NVMe's, the scratch disk is no longer the bottleneck it once was. For all practical purposes the scratch disk is now as fast as RAM. I'm sure there is still a measurable difference, but the point is that you're not waiting for it. By the time you have decided where to put that slider, the data are already available. It was different in the old days with spinning drives. Then you could sometimes go make a cup of coffee while waiting for the scratch disk to catch up.

Be aware that RAM should saturate up to the limit set in preferences, and this will happen fast. That is normal and desirable. Free RAM is wasted RAM.

I consider 32 GB sufficient these days. That's what I have in both my machines, and I work on 5 - 10 GB files routinely. No problems whatsoever. But I do have terabytes of fast scratch disk space.

[Gene27167201cqus]

@Trevor.Dennis 

Btw when you mention the 7s for timing, whats considered a standrad no lag baseline to work off of?