# Why am I getting high CPU usage?

**URL:** <https://forums.unrealengine.com/t/why-am-i-getting-high-cpu-usage/311239>\
**Category:** Programming & Scripting\
**Tags:** unreal-engine\
**Created:** [March 16, 2015, 6:17pm UTC](https://forums.unrealengine.com/t/why-am-i-getting-high-cpu-usage/311239 "2015-03-16T18:17:29Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![anonymous\_user\_d006244e](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_d006244e](https://forums.unrealengine.com/u/anonymous_user_d006244e)\
**Post date:** [March 16, 2015, 6:17pm UTC](https://forums.unrealengine.com/t/why-am-i-getting-high-cpu-usage/311239/1 "2015-03-16T18:17:29Z")

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Hello guys, I’m playing around in the UE4 engine because I plan to use it in the near future but I’ve noticed that my CPU Usage goes all the way up to 100% every time I compile shaders. I don’t understand why because I’m connected to a decent GPU (760 superclocked) and my CPU is a 4690k. I also noticed that it uses approximately 50% of my CPU when not compiling shaders. Is this normal or is there a setting somewhere I have to change? Thanks for the help in advance.

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**Author:** ![anonymous\_user\_e391b7bc](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_e391b7bc](https://forums.unrealengine.com/u/anonymous_user_e391b7bc)\
**Post date:** [March 19, 2015, 1:48am UTC](https://forums.unrealengine.com/t/why-am-i-getting-high-cpu-usage/311239/2 "2015-03-19T01:48:40Z")

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The short answer is yes this is normal. As far as I know shaders go thru your processor before being sent out to your graphics card. There’s ways to have a GPU compute shaders directly (google CUDA/GPGPU etc) but for a game engine it’s very common to rely on both. This is similar for building and encoding lighting, where each thread in your CPU takes on Unreal’s Lightmass.

References:

> <https://gamedev.stackexchange.com/questions/92526/how-do-i-control-which-calculations-are-done-on-the-cpu-and-which-are-done-on-th>

> <https://stackoverflow.com/questions/7212231/are-opengl-shaders-compiled-on-the-gpu-or-the-cpu-how-does-binary-output-vary-b>

> **[General-purpose computing on graphics processing units](https://en.wikipedia.org/wiki/General-purpose_computing_on_graphics_processing_units)**
>
> General-purpose computing on graphics processing units (GPGPU, or less often GPGP) is the use of a graphics processing unit (GPU), which typically handles computation only for computer graphics, to perform computation in applications traditionally handled by the central processing unit (CPU). The use of multiple video cards in one computer, or large numbers of graphics chips, further parallelizes the already parallel nature of graphics processing.
> Essentially, a GPGPU pipeline is a kind of par...