Scratch Disk For Photoshop?

Anything the reduces latency will help performance how much it improve performance at what cost enter is more a value issue.  Justerforcation may depent on the type of work one dose.   If one is dealing with giga pixels image with many layer any improvement in performabce may be preceived by the user and may justify the cost. If you deal with small image and files you may precieve no improvement in performance for the computer is for the most part waiting on you to give it work to do when you are manually using Photoshop UI.

Only Adobe has access to Photoshop code and design. We are uses id Adobe Software. All we can tell you for sure is Photoshop is a resource hungry application. And the way you configurable it can cause it toe be very hungry.  Some things are very expensive like History states. If you keep hundreds for open documents  Photoshop will need to use  more RAM and scratch space. Opening smart object and Photoshop will use temp space. Only some features make use of your GPU. So how you use Photoshop greatly influences Photoshop's operation. There is not a single Photoshop workflow.

Use some system monitor and observe what is going on when you use Photoshop.

The scratch disk is the single most important component in the entire Photoshop ecosystem.

Everything in Photoshop is written to the scratch disk, as far back as your history states go. That's the main memory.

RAM is a fast access cache to the scratch disk. It used to be very important because disks were slow. Now, with the ridiculously fast NVMe drives, that's no longer a practical consideration and there's little reason to have excessive amounts of RAM.

The general advice today, for best performance, is to have the scratch disk on the system drive (NMVe SSD). A separate scratch drive is no longer advised (as it was with spinning drives).

AlanLovesComputers  wrote What are the advantages to having a scratch disk on an SSD for your workflow? Do you guys ever come across a situation where you found you were bottle-necked by the RAM capacity in your workflow?

What sort of work do you do?  From my experience, if you get int complex projects with lots of layer, lots of Smart Objects (Especially if you use nested Smart Objects) and I have a sneaky suspicion that if those Smart Objects contain vector layers, you want to do the very best you can regarding a Scratch disk.

To give you some perspective I currently run a i9-7900X with 64Gb of the best memory I could find, and an RTX2070.  Both the boot and scratch drives are Samsung 512Gb 960PRO NVMe drives.  This is the sort of performance they deliver:

I can still get bogged down with substantial temporary Photoshop files on the scratch drive, and noticeable lag.  It's not terrible, but even with the performance shown above, picking out the bits it needs from a 10Gb temp file is going to take a second or two.

So do use an SSD or NVMe drive for Scratch space.  You don't need to dedicate an SSD entirely to scratch space, but make sure it has plenty of space, and keep your data and program files on a different drive.

For real world best choice hardware for all types of content creation, check out Puget Systems

https://www.pugetsystems.com/all_articles.php

The main advantage of a scratch disc is that Photoshop will work if you have one... I would not recommend putting it on the SSD unless that is the only option i.e if your system includes a spinning rust then that is where you are best to place the scratch

Photoshop Always use scratch space so you would want writing and reading it to be as the best performance possible to reduce latency.  SSD will outperform your  brown and round disk. If Find most Of the time I that Photoshop it will use around 10GB of Rams where it will use many times that amount of Scratch space.   Temp space is also better on SSD than Disk  Photoshop also uses temp space for work file when you do things like open smart objects. Disk Performance can vary depending on devices, system configuration and caching and fragmentation.