Warmup system to speed up startup.

Robust.Client/ClientWarmup.cs

@@ -0,0 +1,28 @@
+using System.Threading.Tasks;
+using Robust.Shared;
+using Robust.Shared.Resources;
+using SixLabors.ImageSharp;
+
+namespace Robust.Client;
+
+/// <summary>
+/// Logic for "warming up" things like slow static constructors concurrently.
+/// </summary>
+internal static class ClientWarmup
+{
+    public static void RunWarmup()
+    {
+        Task.Run(WarmupCore);
+    }
+
+    private static void WarmupCore()
+    {
+        // Get ImageSharp loaded.
+        _ = Configuration.Default;
+
+        SharedWarmup.WarmupCore();
+
+        // Preload the JSON loading code.
+        RsiLoading.Warmup();
+    }
+}

Robust.Client/GameController/GameController.Standalone.cs

@@ -45,6 +45,8 @@ namespace Robust.Client
 
         private static void ParsedMain(CommandLineArgs args, bool contentStart, IMainArgs? loaderArgs, GameControllerOptions options)
         {
+            ClientWarmup.RunWarmup();
+
             var deps = IoCManager.InitThread();
             var mode = args.Headless ? DisplayMode.Headless : DisplayMode.Clyde;
 

Robust.Server/Program.cs

@@ -48,6 +48,8 @@ namespace Robust.Server
 
         private static void ParsedMain(CommandLineArgs args, bool contentStart, ServerOptions options)
         {
+            ServerWarmup.RunWarmup();
+
             Thread.CurrentThread.Name = "Main Thread";
             var deps = IoCManager.InitThread();
             ServerIoC.RegisterIoC(deps);

Robust.Server/ServerWarmup.cs

@@ -0,0 +1,20 @@
+using System.Threading.Tasks;
+using Robust.Shared;
+
+namespace Robust.Server;
+
+/// <summary>
+/// Logic for "warming up" things like slow static constructors concurrently.
+/// </summary>
+internal static class ServerWarmup
+{
+    public static void RunWarmup()
+    {
+        Task.Run(WarmupCore);
+    }
+
+    private static void WarmupCore()
+    {
+        SharedWarmup.WarmupCore();
+    }
+}

Robust.Shared/Resources/RsiLoading.cs

@@ -96,6 +96,12 @@ internal static class RsiLoading
         return new RsiMetadata(size, states);
     }
 
+    public static void Warmup()
+    {
+        // Just a random RSI I pulled from SS14.
+        const string warmupJson = @"{""version"":1,""license"":""CC-BY-SA-3.0"",""copyright"":""Space Wizards Federation"",""size"":{""x"":32,""y"":32},""states"":[{""name"":""mono""}]}";
+        JsonSerializer.Deserialize<RsiJsonMetadata>(warmupJson, SerializerOptions);
+    }
 
     internal sealed class RsiMetadata
     {

Robust.Shared/SharedWarmup.cs

@@ -0,0 +1,21 @@
+using System.Runtime.CompilerServices;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Maths;
+
+namespace Robust.Shared;
+
+/// <summary>
+/// Logic for "warming up" things like slow static constructors concurrently.
+/// </summary>
+internal static class SharedWarmup
+{
+    [MethodImpl(MethodImplOptions.NoOptimization)]
+    public static void WarmupCore()
+    {
+        // Color's cctor unironically takes ~12ms.
+        RuntimeHelpers.RunClassConstructor(typeof(Color).TypeHandle);
+
+        // This ends up initializing prometheus-net which takes quite a while.
+        RuntimeHelpers.RunClassConstructor(typeof(EntitySystemManager).TypeHandle);
+    }
+}