diff --git a/build/Build.cs b/build/Build.cs
index 7e2a885..49ee835 100644
--- a/build/Build.cs
+++ b/build/Build.cs
@@ -50,7 +50,21 @@ public T From<T>()
 
     public Solution CurrentSolution => From<IHazSolution>().Solution;
 
-    public IEnumerable<Project> TestProjects => CurrentSolution.GetAllProjects("*Tests*");
+    public bool IsMacOs =>
+        System.Runtime.InteropServices.RuntimeInformation.IsOSPlatform(System.Runtime.InteropServices.OSPlatform.OSX);
+
+    public bool IsWindows =>
+        System.Runtime.InteropServices.RuntimeInformation.IsOSPlatform(System.Runtime.InteropServices.OSPlatform.Windows);
+
+    public IEnumerable<Project> UnitTests =>
+        CurrentSolution.GetAllProjects("*UnitTests");
+
+    public IEnumerable<Project> ExecutionTests =>
+        CurrentSolution.GetAllProjects("*ExecutionTests");
+
+    // Run only unit tests in CI on Windows & MacOS beecause execution tests take a while.
+    public IEnumerable<Project> TestProjects =>
+        IsServerBuild && (IsMacOs || IsWindows) ? UnitTests : UnitTests.Concat(ExecutionTests);
 
     bool IUseCsharpier.UseGlobalTool => false;
     bool IUseFantomas.UseGlobalTool => false;