When you profile your application, there are some common issues that you might come across. This page outlines how to investigate the cause of some common performance issues.
When looking at a trace of start-up times, there are two key methods to inspect: UnityInitApplicationGraphics
and UnityLoadApplication
. These two methods are the primary places where the configuration, assets, and code of a project can impact start-up time.
Note: The start-up time of your application differs from platform to platform. On most platforms, start up happens while the splash screen appears.
In the above screenshot from an Instruments trace of an example Unity project running on an iOS device, in the platform-specific startUnity
method, note the UnityInitApplicationGraphics
and UnityLoadApplication
methods.
UnityInitApplicationGraphics
performs a lot of internal work, such as setting up the graphics device and initializing a lot of Unity’s internal systems. It also initializes the Resources system by loading an index of all the files contained in the Resources system.
Unity’s Resource system includes every asset file in its data that’s in the Resources
folder in the Assets
folder of your project. This includes any files in the Resources
folder’s children folders. As such, the time required to initialize the Resources system increases in correlation with the number of files within the Resources
folders in your application’s project.
UnityLoadApplication
contains methods that load and initialize the first SceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
See in Glossary in the project. This includes deserializing and instantiating the data necessary to display the first Scene, such as compiling ShadersA program that runs on the GPU. More info
See in Glossary, uploading Textures and instantiating GameObjectsThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary. Also, Unity executes the Awake
callbacks of all MonoBehaviour
s in the first Scene.
These processes mean that if there is any long-running code in an Awake
callback in the first Scene of a project, that code could be responsible for slowing down the project’s initial start-up time. Resolving this involves either eliminating the slow code, or executing it elsewhere in the application’s lifecycle.
For profiling traces captured after the initial startup time, the primary place of interest is the method PlayerLoop
. This is Unity’s main loop, and the code within it runs once per frame.
The above screenshot illustrates several of the most performance-impacting methods within PlayerLoop
. Note: The names of methods within the PlayerLoop
might vary between Unity versions.
PlayerRender
is the method that runs Unity’s rendering system. This includes culling objects, calculating dynamic batches, and submitting drawing instructions to the GPU. Any Image Effects or rendering-based script callbacks (OnWillRenderObject, for example) also run here. In general, this should be the top consumer of CPU time while the project is interactive.
BaseBehaviourManager
calls three templated versions of CommonUpdate
. These invoke certain callbacks within the MonoBehaviour
s attached to active GameObjects in the current Scene:
CommonUpdate<UpdateManager>
calls Update
callbacksCommonUpdate<LateUpdateManager>
calls LateUpdate
callbacksCommonUpdate<FixedUpdateManager>
calls FixedUpdate
if the physics system has tickedIn general, BaseBehaviourManager::CommonUpdate<UpdateManager>
is the most useful method family to inspect, because it’s the entry point for most of the script code running within a Unity project.
There are several other methods that are useful to inspect:
UI::CanvasManager
invokes several different callbacks if a project uses the UGUI system. This includes Unity UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More infoCanvasManager
to appear in the ProfilerA window that helps you to optimize your game. It shows how much time is spent in the various areas of your game. For example, it can report the percentage of time spent rendering, animating, or in your game logic. More infoDelayedCallManager::Update
runs coroutines.PhysicsManager::FixedUpdate
runs the PhysX physics system. This primarily involves running PhysX’s internal code. The number of physics objects in the current Scene, such as Rigidbody
and Collider
influence PhysX’s internal code. Physics-based callbacks also appear here: in particular, OnTriggerStay
and OnCollisionStay
.If the project is using 2D physics, that appears as a similar set of calls under Physics2DManager::FixedUpdate
.
When scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
See in Glossary are invoked on platforms cross-compiled with IL2CPPA Unity-developed scripting back-end which you can use as an alternative to Mono when building projects for some platforms. More info
See in Glossary, look for trace lines that contain a ScriptingInvocation
object. This is the point where Unity’s internal native code transitions into the script runtime to execute script code. Note: Technically, after Unity runs your C# code through IL2CPP, it also becomes native code. However, this cross-compiled code primarily executes methods via the IL2CPP runtime framework and doesn’t resemble handwritten C++.
In the above screenshot, the methods nested beneath the RuntimeInvoker_Void
line are part of cross-compiled C# scripts that Unity executed once per frame.
The trace lines’ names are the name of the original class followed by an underscore and the name of the original method. In this example trace, you can see EventSystem.Update
, PlayerShooting.Update
and several other Update
methods. These are the standard Unity Update
callbacks found in most MonoBehaviours
.
You can expand these methods to see which methods within them consumed CPU time. This includes other script methods within the project, Unity APIs, and C# library code.
The above trace shows that the StandaloneInputModule.Process
method was ray casting through the entire UI once per frame. This method detects whether any touch events were hovering over, or activating any UI elements. The method iterating over all the UI elements, and testing whether the mouse’s position is within their bounding rectangle is resource-intensive.
You can also identify asset loading in CPU traces. The main method that indicates an Asset load is SerializedFile::ReadObject
. This method connects a binary data stream from a file to Unity’s serialization system, which operates via a method named Transfer
. The Transfer
method is on all Asset types, such as Textures, MonoBehaviours and Particle SystemsA component that simulates fluid entities such as liquids, clouds and flames by generating and animating large numbers of small 2D images in the scene. More info
See in Glossary.
The above screenshot is a trace of Unity loading a Scene. When it loads a Scene, Unity reads and deserializes all the Assets within the Scene, as denoted by the calls to various Transfer
methods beneath SerializedFile::ReadObject
.
If you see a performance stutter during runtime and the performance trace shows that SerializedFile::ReadObject
used a significant amount of time, it means that Asset loads reduced the frame rate. Note: SerializedFile::ReadObject
usually appears on the main thread when the SceneManager
, Resources
or AssetBundle APIs request synchronous Asset loads.
To resolve this performance stutter can you can make Asset loading asynchronous (which moves the heavy ReadObject
call to a worker thread), or preload certain heavy Assets.
Transfer
calls also appear when Unity clones objects (denoted by the CloneObject
method in a trace). If a call to Transfer
appears beneath a CloneObject
call, then Unity isn’t loading the Asset from storage. Instead, Unity transfers the old object’s data to the new object. To do this, Unity serializes the old object and deserializes the resulting data as the new object.
Did you find this page useful? Please give it a rating:
Thanks for rating this page!
What kind of problem would you like to report?
Thanks for letting us know! This page has been marked for review based on your feedback.
If you have time, you can provide more information to help us fix the problem faster.
Provide more information
You've told us this page needs code samples. If you'd like to help us further, you could provide a code sample, or tell us about what kind of code sample you'd like to see:
You've told us there are code samples on this page which don't work. If you know how to fix it, or have something better we could use instead, please let us know:
You've told us there is information missing from this page. Please tell us more about what's missing:
You've told us there is incorrect information on this page. If you know what we should change to make it correct, please tell us:
You've told us this page has unclear or confusing information. Please tell us more about what you found unclear or confusing, or let us know how we could make it clearer:
You've told us there is a spelling or grammar error on this page. Please tell us what's wrong:
You've told us this page has a problem. Please tell us more about what's wrong:
Thank you for helping to make the Unity documentation better!
Your feedback has been submitted as a ticket for our documentation team to review.
We are not able to reply to every ticket submitted.
When you visit any website, it may store or retrieve information on your browser, mostly in the form of cookies. This information might be about you, your preferences or your device and is mostly used to make the site work as you expect it to. The information does not usually directly identify you, but it can give you a more personalized web experience. Because we respect your right to privacy, you can choose not to allow some types of cookies. Click on the different category headings to find out more and change our default settings. However, blocking some types of cookies may impact your experience of the site and the services we are able to offer.
More information
These cookies enable the website to provide enhanced functionality and personalisation. They may be set by us or by third party providers whose services we have added to our pages. If you do not allow these cookies then some or all of these services may not function properly.
These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance.
These cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites. They do not store directly personal information, but are based on uniquely identifying your browser and internet device. If you do not allow these cookies, you will experience less targeted advertising. Some 3rd party video providers do not allow video views without targeting cookies. If you are experiencing difficulty viewing a video, you will need to set your cookie preferences for targeting to yes if you wish to view videos from these providers. Unity does not control this.
These cookies are necessary for the website to function and cannot be switched off in our systems. They are usually only set in response to actions made by you which amount to a request for services, such as setting your privacy preferences, logging in or filling in forms. You can set your browser to block or alert you about these cookies, but some parts of the site will not then work. These cookies do not store any personally identifiable information.