diff --git a/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/Extensions.cs b/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/Extensions.cs
index 3c6e21b..00858bb 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/Extensions.cs
+++ b/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/Extensions.cs
@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.Drawing;
 using System.Drawing.Imaging;
-using System.Runtime.InteropServices;
 using System.Windows;
 using System.Windows.Media;
 using System.Windows.Media.Imaging;
@@ -37,12 +36,8 @@ namespace QuickLook.Plugin.PDFViewer
             return foundElement;
         }
 
-        [DllImport("gdi32")]
-        private static extern int DeleteObject(IntPtr o);
-
         public static BitmapSource ToBitmapSource(this Bitmap source)
         {
-            var ip = source.GetHbitmap();
             BitmapSource bs = null;
             try
             {
@@ -57,9 +52,9 @@ namespace QuickLook.Plugin.PDFViewer
 
                 bs.Freeze();
             }
-            finally
+            catch
             {
-                DeleteObject(ip);
+                // ignored
             }
 
             return bs;
diff --git a/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PageIdToImageConverter.cs b/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PageIdToImageConverter.cs
index 8d4bbb2..e2662cf 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PageIdToImageConverter.cs
+++ b/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PageIdToImageConverter.cs
@@ -11,7 +11,7 @@ namespace QuickLook.Plugin.PDFViewer
             if (values.Length < 2)
                 throw new Exception("PageIdToImageConverter");
 
-            var zoom = 0.5f;
+            var zoom = 0.3f;
             if (parameter != null)
                 float.TryParse((string) parameter, out zoom);
 
@@ -21,7 +21,13 @@ namespace QuickLook.Plugin.PDFViewer
             var pageId = (int) values[1];
             if (pageId < 0) return null;
 
-            return handle.GetPage(pageId, zoom).ToBitmapSource();
+            var bitmap = handle.GetPage(pageId, zoom);
+            var bs = bitmap.ToBitmapSource();
+            bitmap.Dispose();
+
+            GC.Collect(GC.MaxGeneration, GCCollectionMode.Optimized);
+
+            return bs;
         }
 
         public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
diff --git a/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml b/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml
index 29ea080..d55cc6d 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml
+++ b/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml
@@ -23,7 +23,7 @@
             <ColumnDefinition Width="*" />
         </Grid.ColumnDefinitions>
         <ListBox x:Name="listThumbnails" Grid.Column="0" VirtualizingPanel.ScrollUnit="Item"
-                 ScrollViewer.IsDeferredScrollingEnabled="False"
+                 VirtualizingPanel.IsVirtualizing="True"
                  SelectedIndex="0"
                  Focusable="False"
                  Background="#00FFFFFF"
diff --git a/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml.cs b/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml.cs
index 3618974..e065548 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml.cs
+++ b/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml.cs
@@ -143,7 +143,9 @@ namespace QuickLook.Plugin.PDFViewer
             if (!PdfLoaded)
                 return;
 
-            var image = PdfHandle.GetPage(CurrentPage, ZoomFactor).ToBitmapSource();
+            var bitmap = PdfHandle.GetPage(CurrentPage, ZoomFactor);
+            var image = bitmap.ToBitmapSource();
+            bitmap.Dispose();
 
             pageViewPanelImage.Source = image;
             pageViewPanelImage.Width = pageViewPanelImage.Source.Width;
diff --git a/QuickLook/Plugin/InfoPanel/Extensions.cs b/QuickLook/Plugin/InfoPanel/Extensions.cs
index 09b87ec..eb9f64d 100644
--- a/QuickLook/Plugin/InfoPanel/Extensions.cs
+++ b/QuickLook/Plugin/InfoPanel/Extensions.cs
@@ -1,7 +1,5 @@
-using System;
-using System.Drawing;
+using System.Drawing;
 using System.Drawing.Imaging;
-using System.Runtime.InteropServices;
 using System.Windows.Media;
 using System.Windows.Media.Imaging;
 
@@ -9,16 +7,12 @@ namespace QuickLook.Plugin.InfoPanel
 {
     public static class Extensions
     {
-        [DllImport("gdi32")]
-        private static extern int DeleteObject(IntPtr o);
-
         public static BitmapSource ToBitmapSource(this Bitmap source)
         {
             // BitmapSource.Create throws an exception when the image is scanned backward.
             // The Clone() will make it back scanning forward.
             source = (Bitmap) source.Clone();
 
-            var ip = source.GetHbitmap();
             BitmapSource bs = null;
             try
             {
@@ -33,9 +27,9 @@ namespace QuickLook.Plugin.InfoPanel
 
                 bs.Freeze();
             }
-            finally
+            catch
             {
-                DeleteObject(ip);
+                // ignored
             }
 
             return bs;