Tweak Photoshop's performance on your machine by optimizing your operating system and hardware.
Your computer must meet certain minimum 
system requirements to run Photoshop optimally. Running Photoshop on underpowered or unsupported hardware—for example, on a computer having an incompatible graphics processor (GPU)—may result in performance issues.
If you’re interested in modifying your current hardware setup (or perhaps if you’re buying a new system), use the following information to optimize it for Photoshop.
Use a fast processor
The speed of the computer’s central processing unit, or CPU, limits the processing speed of Photoshop.
Photoshop generally runs faster with more processor cores, although some features take greater advantage of the additional cores than others. However, you’ll get diminishing returns with multiple processor cores: The more cores you use, the less you get from each additional core. Therefore, Photoshop doesn’t run four times as fast on a computer with 16 processor cores as on a computer with four cores. For most users, the increase in performance that more than six cores provide doesn’t justify the increased cost.
If you are running Photoshop in a virtual environment, Photoshop's GPU use can cause performance issues. Virtual machines cannot access the GPU.
Add RAM
Photoshop uses random access memory (RAM) to process images. If Photoshop has insufficient memory, it uses hard-disk space, also known as a scratch disk, to process information. Accessing information in memory is faster than accessing information on a hard disk. Therefore, Photoshop is fastest when it can process all or most image information in RAM.
For the latest version of Photoshop, at least 8 GB of RAM is recommended.
For instructions on how you can specify how much RAM to allocate to Photoshop, see Adjust memory usage.
Use a discrete graphics card
A discrete, dedicated graphics card uses its own memory (VRAM), has greater processing power, and doesn't eat up RAM
Ultralight laptops and low end desktops, often use an integrated graphics card that uses less power to preserve battery and shares memory with your CPU.
Use a fast, large disk
Photoshop reads and writes image information to disk when your system doesn’t have enough RAM to contain all of it. The Efficiency indicator can help you determine whether getting a faster hard disk or solid-state disk would improve your performance. If the efficiency number is usually above 95%, spending money on a faster scratch disk has little benefit.
To improve Photoshop performance, use a disk with a fast data transfer rate. For example, use an internal hard disk or an external disk connected directly to your computer.
Network servers (hard disk accessed over a network) have slower data transfer rates and are not recommended for use with Photoshop.
Use a solid-state disk
To gain the greatest benefit from an SSD, use it as the scratch disk. Using it as a scratch disk gives you significant performance improvements if you have images that don’t fit entirely in RAM. For example, swapping tiles between RAM and an SSD is much faster than swapping between RAM and a hard disk.
If your SSD doesn’t have much free space (the scratch file grows bigger than can fit on the SSD), add a secondary or tertiary hard disk. (Add it after the SSD.) Make sure that these disks are selected as scratch disks in the Performance preferences.
Also, SSDs vary widely in performance, much more so than hard disks. Using an earlier, slower drive results in little improvement over a hard disk.
Adding RAM to improve performance is generally more cost effective than purchasing an SSD.
If the Efficiency indicator is already high, an SSD doesn’t improve performance. The lower the Efficiency indicator, the greater the improvement an SSD offers.
Fast RAID 0 arrays also make excellent scratch disks, especially if you use the array exclusively for your scratch disk.
Use the following information to set up and use your operating system efficiently with Photoshop.
Close unnecessary applications and startup items
Other open applications and startup items decrease the amount of memory available to Photoshop. To free up additional memory, quit unnecessary applications, startup items, and extensions.
Run Disk Cleanup (Windows)
From time to time, run Disk Cleanup to remove temporary files and any other files that are not being used.
Defragment the hard disk
Photoshop takes longer to read or write a fragmented file than one saved to a contiguous location.
Solid-state disks do not require defragmenting, because their performance doesn’t degrade significantly with normal levels of fragmentation.
Fragmentation is rarely a problem on macOS, unless you normally run with the drive nearly full.
Turn on automatic OS updates
Updates to the Windows or macOS improve performance and compatibility with applications.
Windows:
macOS:
Set power options
Ensure that Photoshop is using a high-performance graphics card rather than a lower-powered integrated graphics card for computers that have two graphics cards.
To know more about graphics cards, see Troubleshoot Photoshop graphics processor (GPU) and graphics driver issues and Configuring computers with multiple graphics cards.
Changing these settings will use your battery more quickly.