My scene consisted of my Camaro with no textures, materials, or ambient occlusion which would increase the rendering time. Rendering times are an average of three trials. Green shows the fastest, blue shows the default settings, Red is slowest. All blue times should be the same, or at least close to it.

Here are the default settings if you are interested:

The default size is the same as the PAL size. However, the default settings are different than the settings that are set when Blender opens and what is above. Format has no effect what-so-ever because this only sets what you can save the render as after rendering is complete. =

Be careful with this setting. This can change the render times drastically, but it will also change the quality of your render drastically as well.

No real difference was found until the Box setting and even that wasn’t much. Theoretically, Mitch and/or CatRom should take the longest and it goes faster as you go down the list since they make the cleanest edge.

Turning Fields off is much faster and I could not tell any difference between the render qualities. Filter Size seems to have no real effect on render times.

It’s very easy to see the changes with this setting. However, the more complex your scene is, the higher you should have this setting for best times. I am not sure when to change this setting when it comes to size or poly-count and from what I have found no one really does. No apparent image quality changes with this setting.

My test used a model with 35k vertices and 38k faces, just for reference.

Ambient Occlusion can make your scene look incredibly better or slightly better depending on the circumstances. The higher setting you give ambient occlusion the longer it will take. The following are the only settings that seem to change the render times drastically. As you can see below, this test showed a render that took over 25 times longer than the default, however with a setting that high there is no graininess.

Now I tested the three major AO settings. For my test, the QMC’s were about the same. Once again, different circumstances can change that. For instance, Adaptive is faster if you use the threshold setting as shown later on. Constant Jitter will be the fastest but the quality is the worst. It’s good for testing though.

Adaptive QMC: Threshold
Basically the higher this you set this setting the faster the render is going to be. Threshold stops Blender from Rendering all of the areas that need AO, therefore less calculating and faster renders. The higher you set this, or the more you omit from calculations, the faster your render will be. With the use of this setting, it can be faster than Constant unlike the times above.

The other settings in Ambient Occlusion did not seem to create any change in the amount of time it took to render, so use them as you see fit.

There are many other settings that will lengthen the rendering time. Here is a list of those that I know will increase your rending time:

Using no textures will be the fastest. Once you begin adding textures to your models or scenes the rendering time will increase. The amount of increase depends on what texture you use. If you use one of the built in settings this will render only a little slower than without it. If you use an image, it all depends on the resolution of the image you are using. The higher the resolution the slower your render is going to be.

Just adding color to your scenes will hardly affect your render time at all. However a few settings can drastically change the length of time you are waiting. Using ‘Ray Mirror’, ‘Ray Transp’ or ‘ZTransp’, or Subsurface Scattering will all slow the rendering down. ZTransp is going to be faster than RayTransp but by using ZTransp you sacrifice the use of all the settings available with Ray Transp’.
        Subsurface Scattering will slow your render down, however it calculates before the actual rendering begins. When using Subsurface Scattering it will ‘render’ the parts of the scene that uses it, then actually finishes your render.

Radiosity is another setting that will calculate before your scene will actually begin to render. The time it takes mainly depends on the ‘Max Iterations’ setting. The higher this setting the longer it will take. Blender recommends a setting of at least 100. If you leave this at zero, it will take forever (I’ve never waited long enough to see how far it would go). I never leave it at zero.

The more complex your scene is the longer it will take to render. One object will be much faster than 1000 objects. The same goes for one object with 8 vertices compared to an object that has 100,000 vertices. Also, the more of the world background you leave open the faster your render will be. The world background renders extremely quickly.

This one is the most obvious. Instead of doing one render, you are doing hundreds so naturally it will take longer. However, if you are rendering for the Video Sequence Editor it will be very fast compared to a standard animation. The stuff in the video sequence editor is typically already rendered the standard way or is an imported video.