adjust simultaneous image extractions

MediaBrowser.Controller/MediaInfo/FFMpegManager.cs

@@ -145,7 +145,7 @@ namespace MediaBrowser.Controller.MediaInfo
         /// <summary>
         /// The video image resource pool count
         /// </summary>
-        private const int VideoImageResourcePoolCount = 1;
+        private const int VideoImageResourcePoolCount = 2;
 
         /// <summary>
         /// The FF probe resource pool

MediaBrowser.Model/Configuration/ServerConfiguration.cs

@@ -280,6 +280,7 @@ namespace MediaBrowser.Model.Configuration
             HttpServerPortNumber = 8096;
             LegacyWebSocketPortNumber = 8945;
             EnableHttpLevelLogging = true;
+            EnableDashboardResponseCaching = true;
 
 #if (DEBUG)
             EnableDeveloperTools = true;