diff --git a/MemoizR.Reactive/Reaction.cs b/MemoizR.Reactive/Reaction.cs
index b9db515..3027f39 100644
--- a/MemoizR.Reactive/Reaction.cs
+++ b/MemoizR.Reactive/Reaction.cs
@@ -16,8 +16,7 @@ internal Reaction(Func<Task> fn, Context context, TaskScheduler? sheduler = null
         this.State = CacheState.CacheDirty;
         this.label = label;
 
-        // The reaction must be initialized to build the Sources.
-        Update().GetAwaiter().GetResult();
+        _ = Init();
     }
 
     public void Pause()
@@ -31,6 +30,15 @@ public Task Resume()
         return UpdateIfNecessary();
     }
 
+    private async Task Init()
+    {
+        using (await context.contextLock.UpgradeableLockAsync())
+        {
+            // The reaction must be initialized to build the Sources.
+            await Update();
+        }
+    }
+
     // Update the reaction if dirty, or a parent turns out to be dirty.
     internal async Task UpdateIfNecessary()
     {
@@ -77,7 +85,7 @@ private async Task Update()
             State = CacheState.CacheDirty;
             return;
         }
-        
+
         // Evaluate the reactive function body, dynamically capturing any other reactives used.
         var prevReaction = context.CurrentReaction;
         var prevGets = context.CurrentGets;
@@ -91,7 +99,7 @@ private async Task Update()
         {
             if (!isPaused)
             {
-                var t = sheduler != null
+                var t = sheduler != null && sheduler.Id != Thread.CurrentThread.ManagedThreadId
                             ? Task.Factory.StartNew(async () => await fn(), CancellationToken.None, TaskCreationOptions.None, sheduler)
                             : fn();
 
@@ -122,7 +130,7 @@ private async Task Update()
                     var source = Sources[i];
                     if (!source.Observers.Any())
                     {
-                        source.Observers = (new[] { this }).ToArray();
+                        source.Observers = new[] { this };
                     }
                     else
                     {
diff --git a/MemoizR.StructuredConcurrency/ConcurrentMapReduce.cs b/MemoizR.StructuredConcurrency/ConcurrentMapReduce.cs
index 4a1629c..ac1a85a 100644
--- a/MemoizR.StructuredConcurrency/ConcurrentMapReduce.cs
+++ b/MemoizR.StructuredConcurrency/ConcurrentMapReduce.cs
@@ -127,7 +127,7 @@ private async Task Update()
                     var source = Sources[i];
                     if (!source.Observers.Any())
                     {
-                        source.Observers = (new[] { this }).ToArray();
+                        source.Observers = new[] { this };
                     }
                     else
                     {
diff --git a/MemoizR.StructuredConcurrency/StructuredJobBase.cs b/MemoizR.StructuredConcurrency/StructuredJobBase.cs
index 9a478fd..52ec461 100644
--- a/MemoizR.StructuredConcurrency/StructuredJobBase.cs
+++ b/MemoizR.StructuredConcurrency/StructuredJobBase.cs
@@ -24,7 +24,7 @@ public async Task<T> Run()
                 AddConcurrentWork();
                 tasks = this.tasks;
             }
-            await Task.WhenAll(tasks.ToArray());
+            await Task.WhenAll(tasks);
             return result!;
         }
         catch
diff --git a/MemoizR/MemoizR.cs b/MemoizR/MemoizR.cs
index 2001066..876f389 100644
--- a/MemoizR/MemoizR.cs
+++ b/MemoizR/MemoizR.cs
@@ -124,7 +124,7 @@ private async Task Update()
                     var source = Sources[i];
                     if (!source.Observers.Any())
                     {
-                        source.Observers = (new[] { this }).ToArray();
+                        source.Observers = new[] { this };
                     }
                     else
                     {