Improve folder enumeration speed (#4199)

Author: gave92

Files/Helpers/FileListCache/FileListCacheController.cs

@@ -94,10 +94,10 @@ public Task SaveFileDisplayNameToCache(string path, string displayName)
         {
             if (displayName == null)
             {
-                filesCache.Remove(path);
+                fileNamesCache.Remove(path);
                 return persistentAdapter.SaveFileDisplayNameToCache(path, displayName);
             }
-            filesCache.Set(path, displayName, new MemoryCacheEntryOptions
+            fileNamesCache.Set(path, displayName, new MemoryCacheEntryOptions
             {
                 Size = 1
             });

Files/ViewModels/FolderSettingsViewModel.cs

@@ -94,17 +94,20 @@ public bool IsLayoutModeChanging
             set => SetProperty(ref isLayoutModeChanging, value);
         }
 
-        public Type GetLayoutType(string folderPath)
+        public Type GetLayoutType(string folderPath, bool isPageNavigationInProgress = true)
         {
-            var oldLayoutMode = LayoutPreference.LayoutMode;
-            LayoutPreference = GetLayoutPreferencesForPath(folderPath);
-            if (oldLayoutMode != LayoutPreference.LayoutMode)
+            var prefsForPath = GetLayoutPreferencesForPath(folderPath);
+            if (isPageNavigationInProgress)
             {
-                IsLayoutModeChanging = true;
+                if (LayoutPreference.LayoutMode != prefsForPath.LayoutMode)
+                {
+                    IsLayoutModeChanging = true;
+                }
+                LayoutPreference = prefsForPath;
             }
 
             Type type = null;
-            switch (LayoutMode)
+            switch (prefsForPath.LayoutMode)
             {
                 case FolderLayoutModes.DetailsView:
                     type = typeof(GenericFileBrowser);