Why doesn't Photoshop run faster?
There are many factors that contribute to the responsiveness of Photoshop. From hardware to software, there a nearly an infinite number of combinations that can boost or hinder Photoshop as it tries to work. Considering factors like how much RAM you have only begins to scratch the surface. Then you have to look at how fast the RAM is and how fast the motherboard will be in supporting it. A computer can only run as fast as its slowest components. Additionally, the hardware resources must be split between all of the running applications. And while you may only be running a web browser at the same time as Photoshop, what about all of the applications running in the background? Security software such as antivirus remains hidden, operating behind the scenes, but it still takes up CPU cycles and RAM. And what about the files you are working with? What are their pixel dimensions? File size on disk? Number of layers, smart objects, styles, and adjustments?
To start, though, you must make sure you meet or exceed the minimum system requirements:
What can I do to make Photoshop run more efficiently?
There are many factors to take into consideration and may steps that can be taken. Here are a list of resources that go into great detail.
What about Photoshop taking advantage of the power of my video card?
With each new release of Photoshop, it will take more advantage of you GPU (Graphic Processing Unit), which can process display information much faster than your CPU. You video card also has its own separate RAM (known as VRAM) for storing this information. However, not all video cards are equal, even if they have the same amount of VRAM. There are different display processing technologies that all video cards do not have access to. These include technologies like OpenGL, OpenCL, and Shader Model. And these technologies have different versions that your video card may or may not have.
For more information on Photoshop's use of GPU, please review:
What other performance boosts has Photoshop gained recently?
While Photoshop tends to gain overall performance upgrades by cleaning up the code to make things run more smoothly with each release, there are a couple new technologies that Photoshop has taken advantage of: