diff --git a/manual/source/themes.rst b/manual/source/themes.rst
index 8dd4175..a8a9e92 100644
--- a/manual/source/themes.rst
+++ b/manual/source/themes.rst
@@ -38,7 +38,9 @@ type: Solid Color, Gradient, or Image.
 
 **Image:** 
     You have the ability to use an image for your background. OpenLP accepts a 
-    variety of image types.  
+    variety of image types. JPG is the most common format of images but can 
+    cause previews to be slow. If you experience this you may want to convert
+    your image to PNG as it previews quicker than other formats.	
 
 .. image:: /pics/theme_manager_image.png
 
diff --git a/manual/source/troubleshooting.rst b/manual/source/troubleshooting.rst
index 08fff3f..63428e1 100644
--- a/manual/source/troubleshooting.rst
+++ b/manual/source/troubleshooting.rst
@@ -201,5 +201,13 @@ OpenLP is not displaying correctly, or is not on the correct screen
 Please read the documentation on :ref:`dualmonitors`. It is very important to
 have dual monitors setup properly for OpenLP to function as expected.
 
+Previews are slow to load when using a theme with an image background
+---------------------------------------------------------------------
+
+If you are using a JPG formatted image for your background try converting it 
+to another format. There is a notable performance difference between JPG and 
+a format such as PNG. Other formats wrok in OpenLP but PNG is the preferred 
+image format and yields the best performance.
+