Image quality and render speed
Producing rendered images always involves making choices that affect the quality (anti-aliasing and sampling) of the images, the speed with which they are rendered, or both. In other words, there is always a tradeoff between speed and quality.
Improve rendered image quality
You can improve render quality through anti-aliasing and by reducing artifacts and flicker. For more information about anti-aliasing, see Improve rendered image quality and Adjust anti-aliasing.
Improve render speed
You can make adjustments to a number of settings to increase the speed with which the scene, surfaces, and, or shadows render, and the speed with which the camera renders the scene. To find out about strategies to increase rendering speed, see Increase overall rendering speed.
Reduce memory
In some cases, you can also reduce the memory used by the render to decrease rendering times. See Reducing memory usage.