Async loading item images => huge performance improvements for old machines.

Wox/Converters/AsyncConverter.cs

@@ -0,0 +1,38 @@
+using System;
+using System.ComponentModel;
+using System.Threading;
+using System.Windows.Data;
+using System.Windows.Threading;
+
+namespace Wox.Converters
+{
+    public class AsyncTask : INotifyPropertyChanged
+    {
+        public AsyncTask(Func<object> valueFunc)
+        {
+            LoadValue(valueFunc);
+        }
+
+        private void LoadValue(Func<object> valueFunc)
+        {
+            var frame = new DispatcherFrame();
+            ThreadPool.QueueUserWorkItem(delegate
+            {
+            
+                        object returnValue =
+                        AsyncValue = valueFunc();
+                        if (PropertyChanged != null)
+                            PropertyChanged(this, new PropertyChangedEventArgs("AsyncValue"));
+                
+            });
+        }
+
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        public object AsyncValue
+        {
+            get;
+            set;
+        }
+    }
+}