Index: System.Data.SQLite/UnsafeNativeMethods.cs
==================================================================
--- System.Data.SQLite/UnsafeNativeMethods.cs
+++ System.Data.SQLite/UnsafeNativeMethods.cs
@@ -691,15 +691,37 @@
       /// </summary>
       private static string cachedAssemblyDirectory;
 
       /////////////////////////////////////////////////////////////////////////
       /// <summary>
+      /// When this field is non-zero, it indicates the
+      /// <see cref="GetAssemblyDirectory" /> method was not able to locate a
+      /// suitable assembly directory.  The
+      /// <see cref="GetCachedAssemblyDirectory" /> method will check this
+      /// field and skips calls into the <see cref="GetAssemblyDirectory" />
+      /// method whenever it is non-zero.
+      /// </summary>
+      private static bool noAssemblyDirectory;
+
+      /////////////////////////////////////////////////////////////////////////
+      /// <summary>
       /// This is the cached return value from the
       /// <see cref="GetXmlConfigFileName" /> method -OR- null if that method
       /// has never returned a valid value.
       /// </summary>
       private static string cachedXmlConfigFileName;
+
+      /////////////////////////////////////////////////////////////////////////
+      /// <summary>
+      /// When this field is non-zero, it indicates the
+      /// <see cref="GetXmlConfigFileName" /> method was not able to locate a
+      /// suitable XML configuration file name.  The
+      /// <see cref="GetCachedXmlConfigFileName" /> method will check this
+      /// field and skips calls into the <see cref="GetXmlConfigFileName" />
+      /// method whenever it is non-zero.
+      /// </summary>
+      private static bool noXmlConfigFileName;
       #endregion
 
       /////////////////////////////////////////////////////////////////////////
       /// <summary>
       /// For now, this method simply calls the Initialize method.
@@ -847,10 +869,11 @@
           #endregion
 
           lock (staticSyncRoot)
           {
               cachedXmlConfigFileName = null;
+              noXmlConfigFileName = false;
           }
       }
 
       /////////////////////////////////////////////////////////////////////////
       /// <summary>
@@ -874,10 +897,13 @@
 
           lock (staticSyncRoot)
           {
               if (cachedXmlConfigFileName != null)
                   return cachedXmlConfigFileName;
+
+              if (noXmlConfigFileName)
+                  return null;
           }
 
           return GetXmlConfigFileName();
       }
 
@@ -926,10 +952,15 @@
                   cachedXmlConfigFileName = fileName;
               }
 
               return fileName;
           }
+
+          lock (staticSyncRoot)
+          {
+              noXmlConfigFileName = true;
+          }
 
           return null;
       }
 
       /////////////////////////////////////////////////////////////////////////
@@ -1594,10 +1625,11 @@
           #endregion
 
           lock (staticSyncRoot)
           {
               cachedAssemblyDirectory = null;
+              noAssemblyDirectory = false;
           }
       }
 
       /////////////////////////////////////////////////////////////////////////
       /// <summary>
@@ -1620,10 +1652,13 @@
 
           lock (staticSyncRoot)
           {
               if (cachedAssemblyDirectory != null)
                   return cachedAssemblyDirectory;
+
+              if (noAssemblyDirectory)
+                  return null;
           }
 
           return GetAssemblyDirectory();
       }
 
@@ -1647,33 +1682,61 @@
           try
           {
               Assembly assembly = Assembly.GetExecutingAssembly();
 
               if (assembly == null)
+              {
+                  lock (staticSyncRoot)
+                  {
+                      noAssemblyDirectory = true;
+                  }
+
                   return null;
+              }
 
               string fileName = null;
 
 #if PLATFORM_COMPACTFRAMEWORK
               AssemblyName assemblyName = assembly.GetName();
 
               if (assemblyName == null)
+              {
+                  lock (staticSyncRoot)
+                  {
+                      noAssemblyDirectory = true;
+                  }
+
                   return null;
+              }
 
               fileName = assemblyName.CodeBase;
 #else
               if (!CheckAssemblyCodeBase(assembly, ref fileName))
                   fileName = assembly.Location;
 #endif
 
               if (String.IsNullOrEmpty(fileName))
+              {
+                  lock (staticSyncRoot)
+                  {
+                      noAssemblyDirectory = true;
+                  }
+
                   return null;
+              }
 
               string directory = Path.GetDirectoryName(fileName);
 
               if (String.IsNullOrEmpty(directory))
+              {
+                  lock (staticSyncRoot)
+                  {
+                      noAssemblyDirectory = true;
+                  }
+
                   return null;
+              }
 
               lock (staticSyncRoot)
               {
                   cachedAssemblyDirectory = directory;
               }
@@ -1698,10 +1761,15 @@
               {
                   // do nothing.
               }
 #endif
           }
+
+          lock (staticSyncRoot)
+          {
+              noAssemblyDirectory = true;
+          }
 
           return null;
       }
       #endregion