performance improvements

src/main/java/cz/kamma/kfmanager/model/FileItem.java

@@ -16,7 +16,6 @@ public class FileItem {
     private final long size;
     private final Date modified;
     private final boolean isDirectory;
-    private final Icon icon;
     private boolean marked;
     private boolean recentlyChanged;
     private String displayPath;
@@ -33,9 +32,6 @@ public class FileItem {
         this.isDirectory = file.isDirectory();
         this.marked = false;
         this.displayPath = displayPath;
-
-        // Load icon from system
-        this.icon = FileSystemView.getFileSystemView().getSystemIcon(file);
     }
 
     public File getFile() {
@@ -83,10 +79,6 @@ public class FileItem {
                (modified != null ? modified.getTime() == other.modified.getTime() : other.modified == null);
     }
 
-    public Icon getIcon() {
-        return icon;
-    }
-
     public String getPath() {
         return displayPath != null ? displayPath : file.getAbsolutePath();
     }

src/main/java/cz/kamma/kfmanager/ui/FilePanelTab.java

@@ -1045,10 +1045,14 @@ public class FilePanelTab extends JPanel {
     }
 
     public void loadDirectory(File directory, boolean autoSelectFirst, boolean requestFocus) {
-        loadDirectory(directory, autoSelectFirst, requestFocus, null);
+        loadDirectory(directory, null, autoSelectFirst, requestFocus, null);
     }
 
     public void loadDirectory(File directory, boolean autoSelectFirst, boolean requestFocus, final Runnable postLoadAction) {
+        loadDirectory(directory, null, autoSelectFirst, requestFocus, postLoadAction);
+    }
+
+    public void loadDirectory(File directory, List<FileItem> preloadedItems, boolean autoSelectFirst, boolean requestFocus, final Runnable postLoadAction) {
         // Ensure we load an existing directory - try parents if necessary
         File dirToLoad = directory;
         while (dirToLoad != null && !dirToLoad.isDirectory()) {
@@ -1079,7 +1083,7 @@ public class FilePanelTab extends JPanel {
             lastValidBriefColumn = 0;
         }
         
-        List<FileItem> items = createFileItemList(directory);
+        List<FileItem> items = (preloadedItems != null) ? preloadedItems : createFileItemList(directory);
         tableModel.setItems(items);
         
         if (viewMode == ViewMode.BRIEF) {
@@ -1191,7 +1195,8 @@ public class FilePanelTab extends JPanel {
             }
         }
 
-        loadDirectory(currentDirectory, false, requestFocus, () -> {
+        final List<FileItem> itemsToLoad = newItems;
+        loadDirectory(currentDirectory, itemsToLoad, false, requestFocus, () -> {
             // Restore marks and set recentlyChanged flag based on active timestamps
             for (FileItem item : tableModel.items) {
                 if (markedNames.contains(item.getName())) {
@@ -2642,17 +2647,7 @@ public class FilePanelTab extends JPanel {
                     }
                     
                     // Show icon for file names
-                    Icon icon = item.getIcon();
+                    Icon icon = getItemIcon(item);
-                    if (item.getName().equals("..")) {
-                        icon = new UpArrowIcon(getForeground());
-                    } else if (item.isDirectory()) {
-                        if (persistedConfig != null) {
-                            icon = new ColoredFolderIcon(persistedConfig.getFolderColor());
-                        }
-                    } else {
-                        // Use type-specific icon for files
-                        icon = new FileSpecificIcon(FileSpecificIcon.getFileType(item.getName()));
-                    }
 
                     if (viewMode == ViewMode.BRIEF) {
                         // In BRIEF mode all columns are names
@@ -2676,7 +2671,38 @@ public class FilePanelTab extends JPanel {
             fileTable.getColumnModel().getColumn(i).setCellRenderer(renderer);
         }
     }
-    
+
+    private final java.util.Map<String, Icon> iconCache = new java.util.HashMap<>();
+
+    private Icon getItemIcon(FileItem item) {
+        if (item == null) return null;
+        String name = item.getName();
+        if (name.equals("..")) {
+            return new UpArrowIcon(getForeground());
+        }
+        
+        String key;
+        if (item.isDirectory()) {
+            Color folderColor = (persistedConfig != null) ? persistedConfig.getFolderColor() : new Color(255, 203, 111);
+            key = "DIR_" + folderColor.getRGB();
+        } else {
+            key = "FILE_" + FileSpecificIcon.getFileType(name);
+        }
+        
+        Icon cached = iconCache.get(key);
+        if (cached != null) return cached;
+        
+        Icon icon;
+        if (item.isDirectory()) {
+            Color folderColor = (persistedConfig != null) ? persistedConfig.getFolderColor() : new Color(255, 203, 111);
+            icon = new ColoredFolderIcon(folderColor);
+        } else {
+            icon = new FileSpecificIcon(FileSpecificIcon.getFileType(name));
+        }
+        iconCache.put(key, icon);
+        return icon;
+    }
+
     private void updateColumnWidths() {
         if (viewMode == ViewMode.FULL) {
             if (fileTable.getColumnModel().getColumnCount() == 3) {
@@ -2728,7 +2754,7 @@ public class FilePanelTab extends JPanel {
                 int w = fm.stringWidth(display);
                 if (w > maxTextWidth) maxTextWidth = w;
 
-                Icon icon = item.getIcon();
+                Icon icon = getItemIcon(item);
                 if (icon != null) {
                     int iw = icon.getIconWidth();
                     if (iw > maxIconWidth) maxIconWidth = iw;
@@ -3058,6 +3084,7 @@ public class FilePanelTab extends JPanel {
      */
     public void setAppConfig(cz.kamma.kfmanager.config.AppConfig cfg) {
         this.persistedConfig = cfg;
+        iconCache.clear();
         // Apply persisted sort if present
         if (cfg != null) {
             java.util.List<String> multi = cfg.getMultipleSortCriteria();