How to speed up Cycles & render faster

With Blender 3.0 now live for a few months, users have been able to use the new Cycles X renderer which is a huge improvement over the old Cycles. But even with Cycles X, you will encounter several scenarios where you wish you could speed up your renders. I have gathered a few tips for the impatient artists out there, please note that these are for Blender 3.1 and up.

Enable GPU for rendering

Unless you’re doing 3D work on an old laptop with no integrated graphics card, you should always enable your GPU for rendering faster in Cycles. The option can be found under Scene > Device > GPU.

Reduce samples

It might seem like it’s the most obvious step, but surprisingly many people do not reduce the samples from the standard 4096 that’s enabled for Cycles. Back in the day, having a high sample count when rendering was considered a little brag. You would see people post their final renders with the additional “10 000 Samples” included in their title. But with 3.0 came a great built-in denoising tool, which both lowered the required sample amount and sped up rendering times greatly in Cycles.

So just how many samples do you need for your render? That’s like asking how long a string is, it’s something you will have to experiment with. It’s recommended to start low and work your way up, chances are you’ll find a sweet spot where quality doesn’t get noticeably better. And let’s be real, most of you reading this are probably not showing your work on big cinema screens or creating large prints, you don’t need pixel-perfect quality.

Scenes with simple materials

If your scene doesn’t use any complex materials, you can actually lower the sample count by a lot, just check this example below. If you’re using mobile data be wary these images are several MBs.

1 sample @ 1920×1080 (Denoising on) Total time: 3.4 seconds
1000 samples @ 1920×1080 (Denoising on) Total time: 18.37 seconds

Just by looking at the images, without opening them, it’s hard to tell a difference. Even when you open them up and compare them side by side their difference isn’t huge. Yes, the render with 1000 samples has much cleaner shadows, but then again, if you cannot see the difference without zooming in, chances are your viewers won’t see it either.

I have written a post about how to get rid of noise and grain in renders.

Scenes with complex materials

You are unfortunately not this lucky if you’re using more complex materials. When I say complex I mean materials that do more than being a solid color. Subsurface, transparency, translucency, reflections, all these are pretty complex and will require higher sample counts, otherwise you will get artifacts. Here’s a Suzanne made out glass, see the difference a higher sample count makes?

1 sample @ 1920×1080 (Denoising on) Total time: 3.2 seconds
1000 samples @ 1920×1080 (Denoising on) Total time: 18.94 seconds

Here you can easily see the difference it makes, the first image looks noisy and smudgy, while the second with higher samples look much cleaner without any noise. So it really is a balancing game when it comes to sample count, having lower amount will speed your render times, the result might also be degraded (but in some cases not very noticable). Use what you think looks best for the amount time spent!

Reduce the number of polygons in the scene

Here’s another “trick”, reduce the amount of polygons in the scene! I know how easy it is to get stuck thinking every single little mesh needs the highest amount of detail to look realistic, but unless that object is close the camera you won’t notice if it’s high or low poly (most of the time).

I am not saying to go low poly on everything, but reducing the poly count can speed up render times in Cycles quite a lot. And don’t think that a low poly count will ruin the realism of your render, just look at the pros doing photogrammetry, the object look photorealistic yet they’re low poly.

Take a look at this video from Gleb Alexandrov to get an idea:

Reduce the amount of advanced shaders

This is related to the sample count, basically the less advanced shaders are used, the less samples are needed and therefore you get faster render times. This advice might also not always be applicable to your scene.

The gist of it is to reduce advanced shaders that take long to render, if you have a big city scene with tons of glass buildings, lights and other materials, if they’re not up close chances are the viewer won’t notice that the reflections are fake.

A good example of a shader that a lot of people overthink is water. Yes, realistic water has volume to it, caustics, refraction and reflections, but does that mean your material needs to have the same attributes? In my opinion no, especially if water isn’t a focal point of the render. When you’ve blocked out your scene and are applying materials, make the materials as simple as possible to start, if they look good keep them that way.

For example, a simple water shader can be made with a principled BSDF where you play around with the roughness and metallic values, while having a noise texture applied to the normal map. It doesn’t need to be physically accurate to look good in a render. I think a lot of people tend to fall into this type of thinking (including myself) and it’s only hurting your renders (and creativity!).

Made with a noise texture plugged into the bump map. Looks good and takes only a second to render.

Reduce the number of volumes

Volumetrics are cool and can really boost the atmosphere of a render, but they’re also complex and take a while to render. If you’re using volumes to create atmosphere, there’s actually a really neat data pass you can choose called “Mist”. You’ll find it under View Layer Properties > Passes > Data > Mist. When enabling this at first you won’t see any difference in your scene and that’s because this is rendered separately.

Tip: Check out our Mist pass tutorial

To find how the mist pass looks like in realtime, set your viewport shading to either “Material Preview” or “Rendered”, then click the little dropdown arrow next to them, scroll down to Render Pass and choose “mist”.

An example of the mist pass, looks moody right?

You can control how the mist behaves by going into World Properties and scrolling down to “Mist Pass”, there you can change the start distance, depth and fall of. To actually use this in your final render you’ll need to utilize the compositing tab. See Ryan King Arts video on the miss pass below for a more in-depth guide:

Reduce render resolution

This is a very simple tweak that only takes a few seconds to implement and can save you tons of time. Unless you’re working on a big commercial project you don’t really need 8K renders, heck, you rarely need 4K. Remember that most users on the internet have a 1080p monitor still.

This advice might not be applicable if you’re doing videos that are going to be uploaded on a platform like YouTube, then you need the extra resolution to combat the compression of the video.

Use the denoiser

The denoiser tool in Cycles is really handy, because it lets you run a lower sample count than usual. Before the denoiser tool, the only way to get rid of artifacts from rendering with Cycles was to run really high sample counts. You can probably imagine why this was not ideal, especially for large scenes with advanced shaders. And the worst part was that a lot of the artifacts and noise never completely disappeared, which needed you to use 3rd party software.

Below you’ll find a comparison of a Suzanne with a subsurface shader, which always creates tons of noise. I don’t know about you, but I’ll rather wait 10 seconds than a full minute for almost the same result.

1000 samples @ 1920×1080 (Denoising off) Total time: 60.11 seconds
100 samples @ 1920×1080 (Denoising on) Total time: 10.66 seconds

While the denoiser is a great tool to have, it’s also important to note that it’s not a miracle cure. Sometimes you’ll get denoising artifacts if you run too few samples, this is especially apparent on glass-like materials.

Use a render farm for Cycles

Get $20 off your first render with GarageFarm

Another very popular option for speeding up your renders in Cycles is to use a render farm. A render farm is basically letting someone else’s hardware render your scene for you. As the name suggests it’s not one computer, but a whole lot of them that does the heavy lifting for you.

So just how much faster are we talking? Well, imagine you have an animated sequence with a very heavy scene, tons of polygons, heavy shaders, and a 4K resolution. In these conditions, one frame could very well take an hour or so. If the animation is 250 frames long, you can expect to have to render for 250 hours (around 10 days) on your laptop/PC.

If you were to use a render farm instead, you’ll have 100 computers (or nodes as they’re also called) doing one frame each, so the finished render will be done in 2.5 hours instead of 250. Sounds pretty nice right?

There’s a catch, however, although not that big, you have to pay for this service. You can expect the cost for a shorter animated sequence to run you somewhere between $20-$80, depending on several factors. If you want to know more about render farms and how to use them, we have a guide on that here.

Buy a better computer

This might seem like a joke, and it is somewhat, but it’s also the one that can make the most difference. While you can implement all of the tweaks I posted above, it doesn’t guarantee that your render times in cycles will be significantly faster than before. For example, if you’re on a potato laptop without a GPU, you will suffer no matter what because CPU rendering is always the slowest.

It’s the same scenario if you’re on an outdated GPU. While Blender is crazy powerful and is becoming more optimized with each update, it cannot transform something old into something new. In the worst scenario, your only option is to upgrade your parts or buy a brand new computer.

If you’re thinking of buying new we have written two articles on that:

2 Comments

  1. Thank you for a great write up, done most of these but it’s the first time I heard about render farms. Which have you tried and are you happy with the results?

    • Thanks GregD! I have tried GarageFarm and I was very happy with the result. It does however have a slight learning curve to it, meaning a lot of things can go wrong and you’ll waste money if you do not pay attention to which settings you use. I am currently writing an in-depth guide on render farms which will be released later, I will link it under the render farm section on this article.

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