Blender unusably slow, CPU usage 11% and Memory 10%

Hi Folks,

As the title says my blender while in viewport mode (or any other) grinds to a halt if I move, undo, pretty much anything for a good 30 seconds before it does the “ask”.

My CPU and memort usage for the system is very low, both around 10% with Blender being pretty much the only thing running, there isnt anything bacgroud using the rest, its all available pretty much.

CPU is a Ryzen 7 2700X and I have 32GB of RAM, AMD RX 580


Any ideas would be greatly appreciated.


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Hi Steve, you claim 11% CPU usage but I bet it’s actually 100% of a single core used in a single-threaded task.

Upgrading your CPU to a faster one in single core performance is the only change you can make towards an improvement. Other than that, you can only wait for blender to become more optimized and multi threaded in those tasks.

Alternatively if you can find ways to simplify and optimize your scene that might help too.

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according to the numbers of verts , you can use LOD in this blend file to make it run smoothly

I have a scene about the same size, and if you are talking of the undo task, unfortunately you’re not alone, regardless of any CPU. One thing I did notice is that if you have viewport shadows on, this slows things down a bit, so I just use cavity. If you are moving things in a collection that has a lot of verts in edit mode, same thing, it will give you a performance hit, so localizing edits and hiding things you don’t need to see and breaking things down into other collections, helps, however, not on the undo side.