This page contains some simple guidelines for optimzing rendering performance in your application.
Before you make any changes, you must profile your application to identify the cause of the problem. If you attempt to solve a performance problem before you understand its cause, you might waste your time or make the problem worse. Additionally, rendering-related performance problems can occur on the CPU or the GPU. Strategies for fixing these problems are quite different, so it’s important to understand where your problem is before taking any action.
The following article on the Unity Learn site is a comprehensive introduction to graphics performance, and contains information on identifying and fixing problems: Fixing performance problems: Optimizing graphics rendering in Unity games. If you are not yet familiar with this subject, read the article before following any of the advice on this page.
Usually, the greatest contributor to CPU rendering time is the cost of sending rendering commands to the GPU. Rendering commands include draw calls (commands to draw geometry), and commands to change the settings on the GPU before drawing the geometry. If this is the case, consider these options:
Many of these approaches will also reduce the work required on the GPU; for example, reducing the overall number of objects that Unity renders in a frame will result in a reduced workload for both the CPU and the GPU.
There are three main reasons why the GPU might fail to complete its work in time to render a frame.
If an application is limited by fill rate, the GPU is trying to draw more pixels per frame than it can handle. If this is the case, consider these options:
If an application is limited by memory bandwidth, the GPU is trying to read and write more data to its dedicated memory than it can handle in a frame. This usually means that that there are too many or textures, or that textures are too large. If this is the case, consider these options:
If an appliction is limited by vertex processing, this means that the GPU is trying to process more vertices than it can handle in a frame. If this is the case, consider these options:
Sometimes, it might benefit your application to reduce the rendering frame rate. This doesn’t reduce the CPU or GPU cost of rendering a single frame, but it reduces the frequency with which Unity does so without affecting the frequency of other operations (such as script execution).
You can reduce the rendering frame rate for parts of your application, or for the whole application. Reducing the rendering frame rate to prevents unnecessary power usage, prolongs battery life, and prevent device temperature from rising to a point where the CPU frequency may be throttled. This is particularly useful on handheld devices.
If profiling reveals that rendering consumes a significant proportion of the resources for your application, consider which parts of your application might benefit from this. Common use cases include menus or pause screens, turn based games where the game is awaiting input, and applications where the content is mostly static, such as automotive UI.
To prevent input lag, you can temporarily increasse the rendering frame rate for the duration of the input so that it still feels responsive.
注意：VR 应用程序不支持按需渲染 (On Demand Rendering)。如果不渲染每一帧，则会导致视觉效果与头部移动不同步，并可能增加晕动症的风险。