The Photoshop engineers are almost always working on ways to speed things up, with dramatic success in various versions, but the basic fact is that it's a big program and user files are often huge. This is true of any industrial-grade software today, so it's not a peculiarity of Photoshop. The answers to improving performance, therefore, are mostly rooted in hardware, not software.
Some important ways to speed things up are:
1. Use an SSD or Optane hybrid.
2. In preferences, set the primary scratch disk to a different drive than the one that contains the images you're working on, preferably a fast one.
3. Add memory. Photoshop will use every bit of RAM you allow, and the more you give it the less it has to swap to disk when file size gets too big.
4. Upgrade your GPU. Check the Adobe site for compatible units.
5. Upgrade your CPU to a modern, multi-core version. Most of Photoshop is multi-threaded these days, so a 16 core processor will dramatically improve performance over a quad-core. Don't even think about a dual core or quad without hyperthreading if you do serious compositing or many-layered artwork.
If you don't use Photoshop professionally and don't need all of its capabilities, you might want to consider lighter-weight solutions such as Photoshop Elements or Affinity Photo that won't put such a heavy load on your system.
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