diff --git a/src/Orchard.Tests/Environment/Extensions/ExtensionManagerTests.cs b/src/Orchard.Tests/Environment/Extensions/ExtensionManagerTests.cs
index 1d45920e3..8bbbc3806 100644
--- a/src/Orchard.Tests/Environment/Extensions/ExtensionManagerTests.cs
+++ b/src/Orchard.Tests/Environment/Extensions/ExtensionManagerTests.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Linq;
 using Autofac;
 using NUnit.Framework;
+using Orchard.Caching;
 using Orchard.Environment.Extensions;
 using Orchard.Environment.Extensions.Folders;
 using Orchard.Environment.Extensions.Loaders;
@@ -57,6 +58,10 @@ namespace Orchard.Tests.Environment.Extensions {
                 return new ExtensionEntry { Descriptor = entry.Descriptor, ExportedTypes = new[] { typeof(Alpha), typeof(Beta), typeof(Phi) } };
             }
 
+            public void Monitor(ExtensionDescriptor descriptor, Action<IVolatileToken> monitor) {
+                throw new NotImplementedException();
+            }
+
             #endregion
         }
 
diff --git a/src/Orchard/Environment/DefaultOrchardHost.cs b/src/Orchard/Environment/DefaultOrchardHost.cs
index a94d69477..5880281c0 100644
--- a/src/Orchard/Environment/DefaultOrchardHost.cs
+++ b/src/Orchard/Environment/DefaultOrchardHost.cs
@@ -1,10 +1,8 @@
-using System;
 using System.Linq;
 using System.Threading;
 using System.Web.Mvc;
-using Autofac;
 using System.Collections.Generic;
-using Autofac.Features.OwnedInstances;
+using Orchard.Caching;
 using Orchard.Environment.Configuration;
 using Orchard.Environment.Extensions;
 using Orchard.Environment.ShellBuilders;
@@ -17,13 +15,15 @@ using Orchard.Mvc.ViewEngines;
 using Orchard.Utility.Extensions;
 
 namespace Orchard.Environment {
-    public class DefaultOrchardHost : IOrchardHost, IShellSettingsManagerEventHandler, IShellDescriptorManagerEventHandler, IExtensionManagerEvents {
+    public class DefaultOrchardHost : IOrchardHost, IShellSettingsManagerEventHandler, IShellDescriptorManagerEventHandler {
         private readonly ControllerBuilder _controllerBuilder;
 
         private readonly IShellSettingsManager _shellSettingsManager;
         private readonly IShellContextFactory _shellContextFactory;
         private readonly IRunningShellTable _runningShellTable;
         private readonly IProcessingEngine _processingEngine;
+        private readonly IExtensionManager _extensionManager;
+        private readonly ICacheManager _cacheManager;
 
         private IEnumerable<ShellContext> _current;
 
@@ -32,12 +32,15 @@ namespace Orchard.Environment {
             IShellContextFactory shellContextFactory,
             IRunningShellTable runningShellTable,
             IProcessingEngine processingEngine,
+            IExtensionManager extensionManager,
+            ICacheManager cacheManager,
             ControllerBuilder controllerBuilder) {
-            //_containerProvider = containerProvider;
             _shellSettingsManager = shellSettingsManager;
             _shellContextFactory = shellContextFactory;
             _runningShellTable = runningShellTable;
             _processingEngine = processingEngine;
+            _extensionManager = extensionManager;
+            _cacheManager = cacheManager;
             _controllerBuilder = controllerBuilder;
             Logger = NullLogger.Instance;
         }
@@ -117,6 +120,12 @@ namespace Orchard.Environment {
         }
 
         protected virtual void BeginRequest() {
+            _cacheManager.Get("OrchardHost_Extensions",
+                ctx => {
+                    _extensionManager.Monitor(ctx.Monitor);
+                    _current = null;
+                    return "";
+                });
             BuildCurrent();
         }
 
@@ -147,9 +156,5 @@ namespace Orchard.Environment {
         void IShellDescriptorManagerEventHandler.Changed(ShellDescriptor descriptor) {
             _current = null;
         }
-
-        void IExtensionManagerEvents.ModuleChanged(string moduleName) {
-            _current = null;
-        }
     }
 }
diff --git a/src/Orchard/Environment/Extensions/ExtensionManager.cs b/src/Orchard/Environment/Extensions/ExtensionManager.cs
index 1bd388332..f7e15737f 100644
--- a/src/Orchard/Environment/Extensions/ExtensionManager.cs
+++ b/src/Orchard/Environment/Extensions/ExtensionManager.cs
@@ -4,6 +4,7 @@ using System.IO;
 using System.Linq;
 using System.Web;
 using ICSharpCode.SharpZipLib.Zip;
+using Orchard.Caching;
 using Orchard.Environment.Extensions.Folders;
 using Orchard.Environment.Extensions.Helpers;
 using Orchard.Environment.Extensions.Loaders;
@@ -32,6 +33,15 @@ namespace Orchard.Environment.Extensions {
             return _folders.SelectMany(folder => folder.AvailableExtensions());
         }
 
+        private IEnumerable<ExtensionEntry> LoadedModules() {
+            foreach (var descriptor in AvailableExtensions()) {
+                // Extensions that are Themes don't have buildable components.
+                if (String.Equals(descriptor.ExtensionType, "Module", StringComparison.OrdinalIgnoreCase)) {
+                    yield return BuildEntry(descriptor);
+                }
+            }
+        }
+
         public IEnumerable<Feature> LoadFeatures(IEnumerable<FeatureDescriptor> featureDescriptors) {
             return featureDescriptors
                 .Select(featureDescriptor => LoadFeature(featureDescriptor))
@@ -41,9 +51,12 @@ namespace Orchard.Environment.Extensions {
         private Feature LoadFeature(FeatureDescriptor featureDescriptor) {
             var featureName = featureDescriptor.Name;
             string extensionName = GetExtensionForFeature(featureName);
-            if (extensionName == null) throw new ArgumentException(T("Feature {0} was not found in any of the installed extensions", featureName).ToString());
-            var extension = BuildActiveExtensions().Where(x => x.Descriptor.Name == extensionName).FirstOrDefault();
-            if (extension == null) throw new InvalidOperationException(T("Extension ") + extensionName + T(" is not active"));
+            if (extensionName == null)
+                throw new ArgumentException(T("Feature {0} was not found in any of the installed extensions", featureName).ToString());
+
+            var extension = LoadedModules().Where(x => x.Descriptor.Name == extensionName).FirstOrDefault();
+            if (extension == null)
+                throw new InvalidOperationException(T("Extension {0} is not active", extensionName).ToString());
 
             var extensionTypes = extension.ExportedTypes.Where(t => t.IsClass && !t.IsAbstract);
             var featureTypes = new List<Type>();
@@ -141,11 +154,12 @@ namespace Orchard.Environment.Extensions {
             Directory.Delete(targetFolder, true);
         }
 
-        private IEnumerable<ExtensionEntry> BuildActiveExtensions() {
+        public void Monitor(Action<IVolatileToken> monitor) {
             foreach (var descriptor in AvailableExtensions()) {
-                // Extensions that are Themes don't have buildable components.
-                if (String.Equals(descriptor.ExtensionType, "Module", StringComparison.OrdinalIgnoreCase)) {
-                    yield return BuildEntry(descriptor);
+                if (string.Equals(descriptor.ExtensionType, "Module", StringComparison.OrdinalIgnoreCase)) {
+                    foreach (var loader in _loaders) {
+                        loader.Monitor(descriptor, monitor);
+                    }
                 }
             }
         }
diff --git a/src/Orchard/Environment/Extensions/IExtensionManager.cs b/src/Orchard/Environment/Extensions/IExtensionManager.cs
index be0950a66..27cda4808 100644
--- a/src/Orchard/Environment/Extensions/IExtensionManager.cs
+++ b/src/Orchard/Environment/Extensions/IExtensionManager.cs
@@ -1,5 +1,7 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Web;
+using Orchard.Caching;
 using Orchard.Environment.Extensions.Models;
 
 namespace Orchard.Environment.Extensions {
@@ -8,5 +10,6 @@ namespace Orchard.Environment.Extensions {
         IEnumerable<Feature> LoadFeatures(IEnumerable<FeatureDescriptor> featureDescriptors);
         void InstallExtension(string extensionType, HttpPostedFileBase extensionBundle);
         void UninstallExtension(string extensionType, string extensionName);
+        void Monitor(Action<IVolatileToken> monitor);
     }
 }
\ No newline at end of file
diff --git a/src/Orchard/Environment/Extensions/IExtensionManagerEvents.cs b/src/Orchard/Environment/Extensions/IExtensionManagerEvents.cs
deleted file mode 100644
index c7be80e9f..000000000
--- a/src/Orchard/Environment/Extensions/IExtensionManagerEvents.cs
+++ /dev/null
@@ -1,7 +0,0 @@
-using Orchard.Events;
-
-namespace Orchard.Environment.Extensions {
-    public interface IExtensionManagerEvents : IEventHandler {
-        void ModuleChanged(string moduleName);
-    }
-}
\ No newline at end of file
diff --git a/src/Orchard/Environment/Extensions/Loaders/AreaExtensionLoader.cs b/src/Orchard/Environment/Extensions/Loaders/AreaExtensionLoader.cs
index e1dbd06b4..d1d227a0c 100644
--- a/src/Orchard/Environment/Extensions/Loaders/AreaExtensionLoader.cs
+++ b/src/Orchard/Environment/Extensions/Loaders/AreaExtensionLoader.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Linq;
 using System.Reflection;
+using Orchard.Caching;
 using Orchard.Environment.Extensions.Models;
 using Orchard.FileSystems.Dependencies;
 using Orchard.FileSystems.VirtualPath;
@@ -17,6 +18,11 @@ namespace Orchard.Environment.Extensions.Loaders {
 
         public int Order { get { return 50; } }
 
+        public void Monitor(ExtensionDescriptor descriptor, Action<IVolatileToken> monitor) {
+            // We don't need to monitor anything since we are loaded
+            // from the application assembly itself.
+        }
+
         public ExtensionProbeEntry Probe(ExtensionDescriptor descriptor) {
             if (descriptor.Location == "~/Areas") {
                 return new ExtensionProbeEntry {
diff --git a/src/Orchard/Environment/Extensions/Loaders/CoreExtensionLoader.cs b/src/Orchard/Environment/Extensions/Loaders/CoreExtensionLoader.cs
index ab35c9e9a..e69c1f0e9 100644
--- a/src/Orchard/Environment/Extensions/Loaders/CoreExtensionLoader.cs
+++ b/src/Orchard/Environment/Extensions/Loaders/CoreExtensionLoader.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Linq;
 using System.Reflection;
+using Orchard.Caching;
 using Orchard.Environment.Extensions.Models;
 using Orchard.FileSystems.Dependencies;
 using Orchard.FileSystems.VirtualPath;
@@ -20,6 +21,11 @@ namespace Orchard.Environment.Extensions.Loaders {
 
         public int Order { get { return 10; } }
 
+        public void Monitor(ExtensionDescriptor descriptor, Action<IVolatileToken> monitor) {
+            // We don't need to monitor anything since we are loaded
+            // from the core assembly.
+        }
+
         public ExtensionProbeEntry Probe(ExtensionDescriptor descriptor) {
             if (descriptor.Location == "~/Core") {
                 return new ExtensionProbeEntry {
diff --git a/src/Orchard/Environment/Extensions/Loaders/DynamicExtensionLoader.cs b/src/Orchard/Environment/Extensions/Loaders/DynamicExtensionLoader.cs
index 0b5a5580c..89b0aab4e 100644
--- a/src/Orchard/Environment/Extensions/Loaders/DynamicExtensionLoader.cs
+++ b/src/Orchard/Environment/Extensions/Loaders/DynamicExtensionLoader.cs
@@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using Orchard.Caching;
 using Orchard.Environment.Extensions.Models;
 using Orchard.FileSystems.Dependencies;
 using Orchard.FileSystems.VirtualPath;
@@ -9,23 +10,33 @@ namespace Orchard.Environment.Extensions.Loaders {
         private readonly IHostEnvironment _hostEnvironment;
         private readonly IBuildManager _buildManager;
         private readonly IVirtualPathProvider _virtualPathProvider;
+        private readonly IVirtualPathMonitor _virtualPathMonitor;
         private readonly IDependenciesFolder _dependenciesFolder;
 
-        public DynamicExtensionLoader(IHostEnvironment hostEnvironment, IBuildManager buildManager, IVirtualPathProvider virtualPathProvider, IDependenciesFolder dependenciesFolder) {
+        public DynamicExtensionLoader(IHostEnvironment hostEnvironment, 
+            IBuildManager buildManager, 
+            IVirtualPathProvider virtualPathProvider, 
+            IVirtualPathMonitor virtualPathMonitor, 
+            IDependenciesFolder dependenciesFolder) {
             _hostEnvironment = hostEnvironment;
             _buildManager = buildManager;
             _virtualPathProvider = virtualPathProvider;
+            _virtualPathMonitor = virtualPathMonitor;
             _dependenciesFolder = dependenciesFolder;
         }
 
         public int Order { get { return 100; } }
 
+        public void Monitor(ExtensionDescriptor descriptor, Action<IVolatileToken> monitor) {
+            string projectPath = GetProjectPath(descriptor);
+            if (projectPath != null)
+                monitor(_virtualPathMonitor.WhenPathChanges(projectPath));
+        }
+
         public ExtensionProbeEntry Probe(ExtensionDescriptor descriptor) {
-            string projectPath = _virtualPathProvider.Combine(descriptor.Location, descriptor.Name,
-                                                              descriptor.Name + ".csproj");
-            if (!_virtualPathProvider.FileExists(projectPath)) {
+            string projectPath = GetProjectPath(descriptor);
+            if (projectPath == null)
                 return null;
-            }
 
             return new ExtensionProbeEntry {
                 Descriptor = descriptor,
@@ -35,6 +46,18 @@ namespace Orchard.Environment.Extensions.Loaders {
             };
         }
 
+        private string GetProjectPath(ExtensionDescriptor descriptor) {
+            string projectPath = _virtualPathProvider.Combine(descriptor.Location, descriptor.Name,
+                                                       descriptor.Name + ".csproj");
+
+            if (!_virtualPathProvider.FileExists(projectPath)) {
+                return null;
+            }
+
+            return projectPath;
+        }
+
+
         public ExtensionEntry Load(ExtensionProbeEntry entry) {
             if (entry.Loader == this) {
                 var assembly = _buildManager.GetCompiledAssembly(entry.VirtualPath);
diff --git a/src/Orchard/Environment/Extensions/Loaders/IExtensionLoader.cs b/src/Orchard/Environment/Extensions/Loaders/IExtensionLoader.cs
index 15be1f554..ae06342a4 100644
--- a/src/Orchard/Environment/Extensions/Loaders/IExtensionLoader.cs
+++ b/src/Orchard/Environment/Extensions/Loaders/IExtensionLoader.cs
@@ -1,4 +1,5 @@
 using System;
+using Orchard.Caching;
 using Orchard.Environment.Extensions.Models;
 
 namespace Orchard.Environment.Extensions.Loaders {
@@ -6,6 +7,7 @@ namespace Orchard.Environment.Extensions.Loaders {
         int Order { get; }
         ExtensionProbeEntry Probe(ExtensionDescriptor descriptor);
         ExtensionEntry Load(ExtensionProbeEntry descriptor);
+        void Monitor(ExtensionDescriptor descriptor, Action<IVolatileToken> monitor);
     }
 
     public class ExtensionProbeEntry {
diff --git a/src/Orchard/Environment/Extensions/Loaders/PrecompiledExtensionLoader.cs b/src/Orchard/Environment/Extensions/Loaders/PrecompiledExtensionLoader.cs
index 7d51dabc2..2f7ca0655 100644
--- a/src/Orchard/Environment/Extensions/Loaders/PrecompiledExtensionLoader.cs
+++ b/src/Orchard/Environment/Extensions/Loaders/PrecompiledExtensionLoader.cs
@@ -1,4 +1,6 @@
-using System.IO;
+using System;
+using System.IO;
+using Orchard.Caching;
 using Orchard.Environment.Extensions.Models;
 using Orchard.FileSystems.Dependencies;
 using Orchard.FileSystems.VirtualPath;
@@ -11,25 +13,41 @@ namespace Orchard.Environment.Extensions.Loaders {
     public class PrecompiledExtensionLoader : IExtensionLoader {
         private readonly IDependenciesFolder _dependenciesFolder;
         private readonly IVirtualPathProvider _virtualPathProvider;
+        private readonly IVirtualPathMonitor _virtualPathMonitor;
 
-        public PrecompiledExtensionLoader(IDependenciesFolder dependenciesFolder, IVirtualPathProvider virtualPathProvider) {
+        public PrecompiledExtensionLoader(IDependenciesFolder dependenciesFolder, IVirtualPathProvider virtualPathProvider, IVirtualPathMonitor virtualPathMonitor) {
             _dependenciesFolder = dependenciesFolder;
             _virtualPathProvider = virtualPathProvider;
+            _virtualPathMonitor = virtualPathMonitor;
         }
 
         public int Order { get { return 30; } }
 
-        public ExtensionProbeEntry Probe(ExtensionDescriptor descriptor) {
-            var extensionPath = _virtualPathProvider.Combine(descriptor.Location, descriptor.Name, "bin",
+        public void Monitor(ExtensionDescriptor descriptor, Action<IVolatileToken> monitor) {
+            string assemblyPath = GetAssemblyPath(descriptor);
+            if (assemblyPath != null)
+                monitor(_virtualPathMonitor.WhenPathChanges(assemblyPath));
+        }
+
+        public string GetAssemblyPath(ExtensionDescriptor descriptor) {
+            var assemblyPath = _virtualPathProvider.Combine(descriptor.Location, descriptor.Name, "bin",
                                                               descriptor.Name + ".dll");
-            if (!_virtualPathProvider.FileExists(extensionPath))
+            if (!_virtualPathProvider.FileExists(assemblyPath))
+                return null;
+
+            return assemblyPath;
+        }
+
+        public ExtensionProbeEntry Probe(ExtensionDescriptor descriptor) {
+            var assemblyPath = GetAssemblyPath(descriptor);
+            if (assemblyPath == null)
                 return null;
 
             return new ExtensionProbeEntry {
                 Descriptor = descriptor,
-                LastModificationTimeUtc = File.GetLastWriteTimeUtc(_virtualPathProvider.MapPath(extensionPath)),
+                LastModificationTimeUtc = File.GetLastWriteTimeUtc(_virtualPathProvider.MapPath(assemblyPath)),
                 Loader = this,
-                VirtualPath = extensionPath
+                VirtualPath = assemblyPath
             };
         }
 
diff --git a/src/Orchard/Environment/Extensions/Loaders/ProbingExtensionLoader.cs b/src/Orchard/Environment/Extensions/Loaders/ProbingExtensionLoader.cs
index a1dde340a..829055f44 100644
--- a/src/Orchard/Environment/Extensions/Loaders/ProbingExtensionLoader.cs
+++ b/src/Orchard/Environment/Extensions/Loaders/ProbingExtensionLoader.cs
@@ -1,4 +1,6 @@
-using System.IO;
+using System;
+using System.IO;
+using Orchard.Caching;
 using Orchard.Environment.Extensions.Models;
 using Orchard.FileSystems.Dependencies;
 using Orchard.FileSystems.VirtualPath;
@@ -17,6 +19,12 @@ namespace Orchard.Environment.Extensions.Loaders {
 
         public int Order { get { return 40; } }
 
+        public void Monitor(ExtensionDescriptor descriptor, Action<IVolatileToken> monitor) {
+            // We don't monitor assemblies loaded from this probing directory,
+            // because they are just a copy of the assemblies from the module
+            // bin directory.
+        }
+
         public ExtensionProbeEntry Probe(ExtensionDescriptor descriptor) {
             if (!_dependenciesFolder.HasPrecompiledAssembly(descriptor.Name))
                 return null;
diff --git a/src/Orchard/Environment/Extensions/Loaders/ReferencedExtensionLoader.cs b/src/Orchard/Environment/Extensions/Loaders/ReferencedExtensionLoader.cs
index 810c935f0..86d4b8e34 100644
--- a/src/Orchard/Environment/Extensions/Loaders/ReferencedExtensionLoader.cs
+++ b/src/Orchard/Environment/Extensions/Loaders/ReferencedExtensionLoader.cs
@@ -1,8 +1,10 @@
-using System.IO;
+using System;
+using System.IO;
 using System.Linq;
 using System.Reflection;
 using System.Web.Compilation;
 using System.Web.Hosting;
+using Orchard.Caching;
 using Orchard.Environment.Extensions.Models;
 using Orchard.FileSystems.Dependencies;
 
@@ -19,6 +21,11 @@ namespace Orchard.Environment.Extensions.Loaders {
 
         public int Order { get { return 20; } }
 
+        public void Monitor(ExtensionDescriptor descriptor, Action<IVolatileToken> monitor) {
+            // We don't monitor assemblies loaded from the "~/bin" directory,
+            // because they are monitored by the ASP.NET runtime.
+        }
+
         public ExtensionProbeEntry Probe(ExtensionDescriptor descriptor) {
             if (HostingEnvironment.IsHosted == false)
                 return null;
diff --git a/src/Orchard/Orchard.Framework.csproj b/src/Orchard/Orchard.Framework.csproj
index bead55b05..6f77582a6 100644
--- a/src/Orchard/Orchard.Framework.csproj
+++ b/src/Orchard/Orchard.Framework.csproj
@@ -360,7 +360,6 @@
     <Compile Include="FileSystems\VirtualPath\ICustomVirtualPathProvider.cs" />
     <Compile Include="FileSystems\Dependencies\WebFormsExtensionsVirtualPathProvider.cs" />
     <Compile Include="FileSystems\Dependencies\WebFormsExtensionsVirtualFile.cs" />
-    <Compile Include="Environment\Extensions\IExtensionManagerEvents.cs" />
     <Compile Include="Environment\IHostEnvironment.cs" />
     <Compile Include="FileSystems\VirtualPath\IVirtualPathMonitor.cs" />
     <Compile Include="FileSystems\Dependencies\IDependenciesFolder.cs" />