Faster Unity Script Changes
Any significantly complex software editor will have its share of frustrations. For Unity, that little window that says “Hold On …” can be chief among them.
There are several steps between making a code change and having it running. Making it sometimes tricky to diagnos what’s taking so long. Adding to that is each step can casually go by slightly different name: recompile, compile time, domain reloads, “Complete Domain”, reload script assemblies, etc.
Creators under the “Made with Unity” umbrella, like me, want as short a feedback cycle as possible. I want to change my code and have it running right away please.
I’ve curated somethings that can speed up this process when it starts getting slow or freezing altogether. Some of these can break your project; make a good backup before trying them yourself. Your mileage may vary. More details further after the list.
- Unity Editor
Consider updating your current editor version. - External Script Editor
Whether it’s Visual Studio, JetBrains Rider, or something else, getting it up to date may help. - Package Manager
Keep your packages in order. - Library Cache
Clear your cache and let Unity rebuild it. - Better Computer Hardware
- Assembly Definitions
Organize your code better. - Preferences and Settings
Many settings can affect script iterations: Domain Reload, Burst Compilation, Auto Refresh, etc.
Update your Unity Editor
It’s often best to be on the latest version of the Unity Editor for whatever major version you are on. Sometimes an upgrade will help but often not or only minorly. However, this at least helps rule something out.
Back up your project before upgrading your editor version.
Update your External Script Editor
Make sure your “External Script Editor” is up to date. And the Unity plugin or extension, if any, is up to date as well. In my case, this is Visual Studio and the Visual Studio Tools for Unity extension.
Keep Package Manager Tidy
One of your packages could be the culprit. Keep your installed packages tidy by removing things you don’t need. Updating packages that have newer versions may help. Packages can use Unity features like InitializeOnLoad, which can be triggered during Unity’s reloading process.
I’ve found this to be risky as well; read the changelogs and back up your project.
Clear and Rebuild your Library Cache
Inside your Unity project is a “Library” folder, at least on Windows that’s what it’s called. The last time I deleted mine it contained 82K files. After deleting this directory, open your project; it will take much longer to open than usual. That’s because Unity is rebuilding your library cache.
This took my project from around 90K files down to 59K files.
Use Better Computer Hardware
Lots of options to consider: a more powerful GPU, CPU, or memory.
If you have the resources:
- Ditch the laptop and move to a desktop.
Or, even more extreme:
- Move to a workstation platform for more memory channels and more PCI lanes, which can allow for things like m.2 RAID0. (I love my super fast hard drive.)
Use Assembly Definitions
Separate code using Assembly Definitions.
This is also just a good general practice as it forces you to be more thoughtful about what code depends on what other code. And if you ever make more than one Unity game you can consider how to reuse code between projects.
For more one this, the developer behind a game called Tales of Kulplex wrote up a devlog that dives into this topic deeper: Tales of Kulplex, Devlog #6 — Attempting to Decrease Compile Times in Unity
Check Preferences and Settings
The following setting and preferences are known to affect script reloading.
- Turn off the Burst Compilation
- Disable Domain Reloading
In your project settings, under Enter Play Mode Options - Test “Auto Refresh” Preference
https://docs.unity3d.com/2021.1/Documentation/Manual/Preferences.html#General
Other Benefits
Many of the tactics above have other benefits. I was struggling with Unity scene saves taking a long time. Recently, I had that issue go away by working through the steps above.
About
If you found benefits from this article please consider following my game’s development at twitter.com/madjoystudio. Check out my game development origin story: The Adventure Begins: Founding a Game Studio — Part 1
Appendix
Other Options
This came up in my research but I have yet to try it.
- Try Fast Script Reload: https://github.com/handzlikchris/FastScriptReload
Unity Forums
- Long Time stuck on Completing Domain after any code change
- Reloading Script Assemblies takes a long time, and keeps getting slower
- Official: Improving iteration time on C# script changes
- LET’S DEMAND FASTER SCRIPT COMPILATION TIME !!!!!
- Why is “Domain Reload” sooo slow, and will this ever be fixed?
Unity Issue Tracker
- THE CREATING AND IMPORT OF A NEW SCRIPT IN EDITOR BECAME SLOW IN TRUNK
- INCREASED SCRIPT ASSEMBLY RELOAD TIME
