sort per directory level, this is MUCH faster

addons/project/kateprojectitem.cpp

@@ -81,6 +81,19 @@ QVariant KateProjectItem::data(int role) const
     return QStandardItem::data(role);
 }
 
+bool KateProjectItem::operator<(const QStandardItem &other) const
+{
+    // let directories stay first
+    const bool isDirectory = data(Qt::ToolTipRole).isNull();
+    const bool otherIsDirectory = other.data(Qt::ToolTipRole).isNull();
+    if (isDirectory != otherIsDirectory) {
+        return isDirectory > otherIsDirectory;
+    }
+
+    // case-insensitive compare of the filename
+    return data(Qt::DisplayRole).toString().compare(other.data(Qt::DisplayRole).toString(), Qt::CaseInsensitive) < 0;
+}
+
 QIcon *KateProjectItem::icon() const
 {
     if (m_icon) {

addons/project/kateprojectitem.h

@@ -48,6 +48,13 @@ public:
      */
     QVariant data(int role = Qt::UserRole + 1) const override;
 
+    /**
+     * We want case-insensitive sorting and directories first!
+     * @param other other element to compare with
+     * @return is this element less than?
+     */
+    bool operator<(const QStandardItem &other) const override;
+
 public:
     void slotModifiedChanged(KTextEditor::Document *);
     void slotModifiedOnDisk(KTextEditor::Document *document, bool isModified, KTextEditor::ModificationInterface::ModifiedOnDiskReason reason);

addons/project/kateprojectworker.cpp

@@ -167,12 +167,13 @@ void KateProjectWorker::loadFilesEntry(QStandardItem *parent, const QVariantMap
                                }),
                 files.end());
 
+    /**
+     * we might end up with nothing to add at all
+     */
     if (files.isEmpty()) {
         return;
     }
 
-    files.sort(Qt::CaseInsensitive);
-
     /**
      * construct paths first in tree and items in a map
      */
@@ -213,6 +214,12 @@ void KateProjectWorker::loadFilesEntry(QStandardItem *parent, const QVariantMap
     for (const auto &item : qAsConst(item2ParentPath)) {
         item.second->appendRow(item.first);
     }
+
+    /**
+     * sort the stuff once recursively, this is a LOT faster than once sorting the list
+     * as we have normally not all stuff in on level of directory
+     */
+    parent->sortChildren(0);
 }
 
 QStringList KateProjectWorker::findFiles(const QDir &dir, const QVariantMap &filesEntry)