CPU and GPU Usage in Blender

I’ve a had few long articles, let’s keep this one short. Start with the big one:

GPU Usage

Not everything in Blender utilizes the GPU. The main things that do are:

• Rendering. Blender attempts to fit all the data to render your scene on the graphics card, otherwise it has to go back and forth between the CPU, RAM, and hard drive (worse case scenario). This is also why VRAM is so important.

  • Material and Render Preview shading modes in the viewport utilize the GPU too in a similar way

• Compositing, if hardware acceleration is enabled

• Subdivision surfacing, if GPU subdivision is available and enabled

• Drawing Blender’s user interface (UI), which is why rendering from the command line can save you time and memory usage

In terms of tips in better utilizing your GPU, many of the same tips as for saving VRAM, which I discuss here, apply. I could just save my breath here and say to read that article, but to summarize:

• Reduce complexity of anything needed for rendering: geometry count, texture resolution, and complexity of procedural textures

• Reduce load on your graphics card by closing other apps (in other words, maybe don’t game or do a Discord call on the same computer while rendering)

• Render from the command line instead of loading the entire user interface

• In worst case scenarios, either lower your screen’s resolution or refresh rate, or refresh/update your drivers

Also, optimize your viewport. While using material or render shading modes are certainly helpful, they do eat up resources. Use solid shading mode whenever you can. Did you know you can even preview textures in solid shading mode?

Some users complain that their GPU is not at 100% usage, which apparently means Blender is not using it correctly. Unfortunately, you cannot force Blender to use 100% of your graphics card. Blender developers have to code Blender to specifically support graphics cards (including different types of graphics cards) for different operations.

If you're unsure, collect as much info as you can about your computer and the problem, collect even more, and report it as a bug.

CPU Usage

The same complaint about Blender using 100% of your graphics card could also be said about your CPU. While Blender tries to use hardware acceleration and multiple cores when it can, it will not be the case for every operation in Blender. Many operations work on a single core, including much of the user interface.

So, how to improve or manage your CPU performance? You can decide whether the CPU or GPU is utilized for:

• Cycles (and usually just pick one or the other - CPU + GPU tends to be slower)

• Compositor

• Denoising (or just turn denoising off entirely)

So be sure to check Blender's render properties and preferences under the systems tab for those.

One more big tip for the CPU: disable add-ons. Nearly all add-ons rely on Python only, which is mostly run on the CPU. And some add-ons run functions every time you change something in your scene or even update the viewport, making even simple tasks slow. So be sure to only keep the ones enabled that you really need enabled.

That’s it for now, thanks for reading!