diff --git a/rtgui/filmsimulation.cc b/rtgui/filmsimulation.cc
index e1cbd4966..feed0ba35 100644
--- a/rtgui/filmsimulation.cc
+++ b/rtgui/filmsimulation.cc
@@ -148,7 +148,7 @@ int ClutComboBox::fillFromDir (const Glib::ustring& path)
     m_model = Gtk::TreeStore::create (m_columns);
     set_model (m_model);
 
-    const auto result = parseDir (path, nullptr);
+    const auto result = parseDir (path);
 
     if (result > 0) {
         pack_start (m_columns.label, false);
@@ -157,68 +157,113 @@ int ClutComboBox::fillFromDir (const Glib::ustring& path)
     return result;
 }
 
-Gtk::TreeIter appendToModel( Glib::RefPtr<Gtk::TreeStore> model, Gtk::TreeModel::Row *parent )
+int ClutComboBox::parseDir (const Glib::ustring& path)
 {
-    Gtk::TreeIter result;
-
-    if ( parent ) {
-        result = model->append( parent->children() );
-
-    } else {
-        result = model->append();
+    if (path.empty () || !Glib::file_test (path, Glib::FILE_TEST_IS_DIR)) {
+        return 0;
     }
 
-    return result;
-}
+    // Build menu of limited directory structure using breadth-first search
+    using Dirs = std::vector<std::pair<Glib::ustring, Gtk::TreeModel::Row>>;
+    Dirs dirs;
 
-int ClutComboBox::parseDir( Glib::ustring path, Gtk::TreeModel::Row *parentRow )
-{
-    int result = 0;
+    {
+        Dirs currDirs;
+        Dirs nextDirs;
 
-    if ( path.empty() || !safe_file_test( path, Glib::FILE_TEST_EXISTS ) || !safe_file_test ( path, Glib::FILE_TEST_IS_DIR ) ) {
-        return result;
-    }
+        constexpr auto maxDirCount = 128, maxDirDepth = 4;
+        auto dirCount = 0, dirDepth = 0;
 
-    Glib::Dir* dir = new Glib::Dir( path );
+        currDirs.emplace_back (path, Gtk::TreeModel::Row ());
 
-    Strings names;
+        while (!currDirs.empty ()) {
 
-    for( Glib::DirIterator it = dir->begin(); it != dir->end(); ++it ) {
-        Glib::ustring current = *it;
+            for (auto& dir : currDirs) {
 
-        if ( current != "." && current != ".." ) {
-            names.push_back( current );
-        }
-    }
+                const auto& path = dir.first;
+                const auto& row = dir.second;
 
-    std::sort( names.begin(), names.end() );
+                try {
+                    for (const auto& entry : Glib::Dir (path)) {
 
-    for ( Strings::iterator it = names.begin(); it != names.end(); ++it ) {
-        Glib::ustring current = *it;
-        Glib::ustring fullname = Glib::build_filename( path, current );
+                        const auto entryPath = Glib::build_filename (path, entry);
 
-        if ( safe_file_test( fullname, Glib::FILE_TEST_IS_DIR ) ) {
+                        if (!Glib::file_test (entryPath, Glib::FILE_TEST_IS_DIR)) {
+                            continue;
+                        }
 
-            Gtk::TreeModel::Row newFolderMenu = *appendToModel( m_model, parentRow );
-            newFolderMenu[ m_columns.label ] = current;
-            result += parseDir( fullname, &newFolderMenu );
-        } else {
-            Glib::ustring name, extension, profileName;
-            splitClutFilename( current, name, extension, profileName );
+                        auto newRow = row ? *m_model->append (row.children ()) : *m_model->append ();
+                        newRow[m_columns.label] = entry;
 
-            if ( extension == "tif" ||
-                    extension == "TIF" ||
-                    extension == "png" ||
-                    extension == "PNG" ) {
-                Gtk::TreeModel::Row newClut = *appendToModel( m_model, parentRow );
-                newClut[ m_columns.label ] = name;
-                newClut[ m_columns.clutFilename ] = fullname;
-                ++result;
+                        nextDirs.emplace_back (entryPath, newRow);
+                    }
+                } catch (Glib::Exception&) {}
+
+                dirs.push_back (std::move (dir));
+                if (++dirCount > maxDirCount) {
+                    m_model->clear ();
+                    return 0;
+                }
+            }
+
+            currDirs.clear ();
+            currDirs.swap (nextDirs);
+            if (++dirDepth > maxDirDepth) {
+                m_model->clear ();
+                return 0;
             }
         }
     }
 
-    return result;
+    // Fill menu structure with CLUT files
+    Strings entries;
+
+    constexpr auto maxFileCount = 4096;
+    auto fileCount = 0;
+
+    for (const auto& dir : dirs) {
+
+        const auto& path = dir.first;
+        const auto& row = dir.second;
+
+        entries.clear ();
+
+        try {
+            for (const auto& entry : Glib::Dir (path)) {
+                entries.push_back (entry);
+            }
+        } catch (Glib::Exception&) {}
+
+        std::sort (entries.begin (), entries.end ());
+
+        for (const auto& entry : entries) {
+
+            const auto entryPath = Glib::build_filename (path, entry);
+
+            if (!Glib::file_test (entryPath, Glib::FILE_TEST_IS_REGULAR)) {
+                continue;
+            }
+
+            Glib::ustring name, extension, profileName;
+            splitClutFilename (entry, name, extension, profileName);
+
+            extension = extension.casefold ();
+            if (extension.compare ("tif") == 0 && extension.compare ("png") == 0) {
+                continue;
+            }
+
+            auto newRow = row ? *m_model->append (row.children ()) : *m_model->append ();
+            newRow[m_columns.label] = name;
+            newRow[m_columns.clutFilename] = entryPath;
+
+            if (++fileCount > maxFileCount) {
+                m_model->clear ();
+                return 0;
+            }
+        }
+    }
+
+    return fileCount;
 }
 
 Glib::ustring ClutComboBox::getSelectedClut()
diff --git a/rtgui/filmsimulation.h b/rtgui/filmsimulation.h
index a463bdf60..440bf0c9e 100644
--- a/rtgui/filmsimulation.h
+++ b/rtgui/filmsimulation.h
@@ -25,7 +25,7 @@ private:
         ClutColumns();
     };
 
-    int parseDir( Glib::ustring path, Gtk::TreeModel::Row *parentRow );
+    int parseDir (const Glib::ustring& path);
     Gtk::TreeIter findRowByClutFilename(  Gtk::TreeModel::Children childs, Glib::ustring filename );
 
     Glib::RefPtr<Gtk::TreeStore> m_model;