Unity's Mono problem: C# code runs slower than it should
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Unity's Mono problem: C# code runs slower than it should
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Re: Unity's Mono problem: C# code runs slower than it should
#2Yeah I think Unity just doesn't have the technical skillset anymore to make the migration to coreclr. It keeps getting delayed and their tech leads keep dropping out.
Might I suggest https://github.com/stride3d/stride, which is already on .net 10 and doesn't have any cross-boundary overhead like Unity.
Re: Unity's Mono problem: C# code runs slower than it should
#3That's interesting. I made measurements with Mono and CoreCLR some years ago, but only with a single thread, and I came to the conclusion that their performance was essentially the same (see https://rochus.hashnode.dev/is-the-mono-clr-really-slower-th...). Can someone explain what benchmarks were actually used? Was it just the "Simple benchmark code" in listing 1?
Re: Unity's Mono problem: C# code runs slower than it should
#4Will the move to CoreCLR give any speed ups in practice if the release build is complied with IL2CPP anyway? On all the games that I've worked on, IL2CPP is one of the first things that we've enabled, and the performance difference between the editor and release version is very noticeable.
Re: Unity's Mono problem: C# code runs slower than it should
#5The article doesn't cover it but the GC being used by Unity also performs very poorly vs. .NET, and even vs. standalone Mono, because it is using the Boehm GC. Last I heard Unity has no plans to switch IL2CPP to a better GC [1].
It'll be interesting to see how the CoreCLR editor performs. With that big of a speed difference the it might be possible for games to run better in the editor than a standalone Mono/IL2CPP build.
[1] https://discussions.unity.com/t/coreclr-and-net-modernizatio...
Re: Unity's Mono problem: C# code runs slower than it should
#6Yeah I think Unity just doesn't have the technical skillset anymore to make the migration to coreclr. It keeps getting delayed and their tech leads keep dropping out. Might I suggest https://github.com/stride3d/stride , which is already on .net 10 and doesn't have any cross-boundary overhead like Unity.
Progress has been painfully slow, but Unity does seem to be moving forward.
Unity updates on their plans and progress:
2022 - officially announced plans to switch to CoreCLR - https://unity.com/blog/engine-platform/unity-and-net-whats-n...
2023 - Tech update - https://unity.com/blog/engine-platform/porting-unity-to-core...
Unite 2025 - CoreCLR based player scheduled for Unity 6.7 in 2026 - https://digitalproduction.com/2025/11/26/unitys-2026-roadmap...
Re: Unity's Mono problem: C# code runs slower than it should
#7Yeah I think Unity just doesn't have the technical skillset anymore to make the migration to coreclr. It keeps getting delayed and their tech leads keep dropping out. Might I suggest https://github.com/stride3d/stride , which is already on .net 10 and doesn't have any cross-boundary overhead like Unity.
Stride has a fraction of the features as unity.
Godot is the only real open source competitor, their C# support is spotty. If I can't build to Web it's useless for game jams as no one should be downloading and running random binaries.
A real sandbox solution with actual GPU support is needed.
Re: Unity's Mono problem: C# code runs slower than it should
#8The article doesn't cover it but the GC being used by Unity also performs very poorly vs. .NET, and even vs. standalone Mono, because it is using the Boehm GC. Last I heard Unity has no plans to switch IL2CPP to a better GC [1]. It'll be interesting to see how the CoreCLR editor performs. With that big of a speed difference the it might be possible for games to run better in the editor than a standalone Mono/IL2CPP b…
> because it is using the Boehm GC
For what reason? Mono has a pretty good precise GC since many years.
Re: Unity's Mono problem: C# code runs slower than it should
#9The article doesn't cover it but the GC being used by Unity also performs very poorly vs. .NET, and even vs. standalone Mono, because it is using the Boehm GC. Last I heard Unity has no plans to switch IL2CPP to a better GC [1]. It'll be interesting to see how the CoreCLR editor performs. With that big of a speed difference the it might be possible for games to run better in the editor than a standalone Mono/IL2CPP b…
Re. the editor speedup, it should outright eliminate the "domain reload" thingy that happens because all of the C# needs to be unloaded and reloaded in response to a change.
Re: Unity's Mono problem: C# code runs slower than it should
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