diff --git a/src/imagemodel.cpp b/src/imagemodel.cpp
index 3288ae0..622dbf6 100644
--- a/src/imagemodel.cpp
+++ b/src/imagemodel.cpp
@@ -9,7 +9,8 @@
 ImageModel::ImageModel(QObject *parent)
     : QAbstractListModel(parent)
 {
-    m_threadPool.setMaxThreadCount(QThread::idealThreadCount());
+    // Limit 1 thread for thumbnail loading to avoid excessive disk I/O on harddrives. SSDs are so fast the extra threads don't help much anyway.
+    m_threadPool.setMaxThreadCount(1);  //QThread::idealThreadCount()
 
     m_placeholder = QPixmap(128, 128);
     m_placeholder.fill(Qt::lightGray);
@@ -24,12 +25,35 @@ ImageModel::~ImageModel()
     m_threadPool.waitForDone();
 }
 
+void ImageModel::setCacheMaxSize(int n)
+{
+    m_cacheMaxSize = std::max(0, n);
+    while (m_cacheOrder.size() > m_cacheMaxSize)
+        m_folderThumbnailCache.remove(m_cacheOrder.takeFirst());
+}
+
 void ImageModel::setDirectory(const QString &path)
 {
     m_cancelFlag = true;
     m_threadPool.waitForDone();
     m_cancelFlag = false;
 
+    // Save current folder's thumbnails to cache before discarding them
+    if (!m_currentDir.isEmpty()) {
+        ThumbnailMap map;
+        for (const Item &item : m_items)
+            if (item.loaded && !item.isFolder)
+                map[item.path] = item.thumbnail;
+        if (!map.isEmpty()) {
+            if (!m_cacheOrder.contains(m_currentDir)) {
+                m_cacheOrder.append(m_currentDir);
+                if (m_cacheOrder.size() > m_cacheMaxSize)
+                    m_folderThumbnailCache.remove(m_cacheOrder.takeFirst());
+            }
+            m_folderThumbnailCache[m_currentDir] = std::move(map);
+        }
+    }
+
     beginResetModel();
     m_items.clear();
     m_pendingRows.clear();
@@ -61,9 +85,23 @@ void ImageModel::setDirectory(const QString &path)
 
     const auto files = dir.entryInfoList();
 
+    // Restore cached thumbnails for this folder if available
+    const ThumbnailMap *cached = m_folderThumbnailCache.contains(path)
+        ? &m_folderThumbnailCache[path]
+        : nullptr;
+
     for (const QFileInfo &file : files)
     {
-        m_items.append({file.absoluteFilePath(), file.fileName(), m_placeholder, false, false});
+        QPixmap thumb = m_placeholder;
+        bool loaded = false;
+        if (cached) {
+            auto it = cached->find(file.absoluteFilePath());
+            if (it != cached->end()) {
+                thumb = it.value();
+                loaded = true;
+            }
+        }
+        m_items.append({file.absoluteFilePath(), file.fileName(), thumb, loaded, false});
     }
 
     endResetModel();
diff --git a/src/imagemodel.h b/src/imagemodel.h
index 7586159..0be4ed7 100644
--- a/src/imagemodel.h
+++ b/src/imagemodel.h
@@ -5,6 +5,8 @@
 #include <QVector>
 #include <QThreadPool>
 #include <QSet>
+#include <QHash>
+#include <QList>
 #include <atomic>
 #include <QIcon>
 
@@ -24,6 +26,7 @@ public:
     QString currentDirectory() const;
 
     void requestThumbnails(int firstRow, int lastRow);
+    void setCacheMaxSize(int n);
 
     int rowCount(const QModelIndex &parent = QModelIndex()) const override;
     QVariant data(const QModelIndex &index, int role) const override;
@@ -42,6 +45,8 @@ private:
 
     void queueRow(int row);
 
+    using ThumbnailMap = QHash<QString, QPixmap>;
+
     QVector<Item> m_items;
     QThreadPool m_threadPool;
     QPixmap m_placeholder;
@@ -50,4 +55,9 @@ private:
     std::atomic_bool m_cancelFlag{false};
     QIcon m_folderIcon;
     QString m_currentDir;
+
+    // Folder thumbnail cache (last N visited directories)
+    QHash<QString, ThumbnailMap> m_folderThumbnailCache;
+    QList<QString> m_cacheOrder;
+    int m_cacheMaxSize = 4;
 };
diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
index 312c92f..2086083 100644
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -439,6 +439,8 @@ void MainWindow::loadPreferences()
     m_imageView->setBackgroundColor(m_backgroundColorPreference);
     m_lockDockingPreference = settings.value("lockDocking", false).toBool();
     applyDockLocking(m_lockDockingPreference);
+    m_folderCacheSizePreference = settings.value("folderCacheSize", 4).toInt();
+    m_imageModel->setCacheMaxSize(m_folderCacheSizePreference);
     if (settings.contains("windowGeometry"))
         restoreGeometry(settings.value("windowGeometry").toByteArray());
     if (settings.contains("windowState"))
@@ -450,6 +452,7 @@ void MainWindow::savePreferences()
     QSettings settings("SagoImageBrowser", "SagoImageBrowser");
     settings.setValue("backgroundColor", m_backgroundColorPreference);
     settings.setValue("lockDocking", m_lockDockingPreference);
+    settings.setValue("folderCacheSize", m_folderCacheSizePreference);
     settings.setValue("windowGeometry", saveGeometry());
     settings.setValue("windowState", saveState());
 }
@@ -459,6 +462,7 @@ void MainWindow::onPreferencesTriggered()
     PreferencesDialog dialog(this);
     dialog.setBackgroundColor(m_backgroundColorPreference);
     dialog.setLockDocking(m_lockDockingPreference);
+    dialog.setCacheSize(m_folderCacheSizePreference);
 
     bool shouldResetLayout = false;
     connect(&dialog, &PreferencesDialog::resetLayoutRequested, this, [&shouldResetLayout]() {
@@ -471,6 +475,8 @@ void MainWindow::onPreferencesTriggered()
         m_imageView->setBackgroundColor(m_backgroundColorPreference);
         m_lockDockingPreference = dialog.getLockDocking();
         applyDockLocking(m_lockDockingPreference);
+        m_folderCacheSizePreference = dialog.getCacheSize();
+        m_imageModel->setCacheMaxSize(m_folderCacheSizePreference);
         savePreferences();
     }
     
diff --git a/src/mainwindow.h b/src/mainwindow.h
index 76bcf9e..39f127d 100644
--- a/src/mainwindow.h
+++ b/src/mainwindow.h
@@ -52,6 +52,7 @@ private:
 
     QStackedWidget *m_stack;
     QString m_backgroundColorPreference = "black";
+    int m_folderCacheSizePreference = 4;
     QWidget *m_browserPage;
     ImageViewWidget *m_imageView;
     bool m_wasMaximized = false;
diff --git a/src/preferencesdialog.cpp b/src/preferencesdialog.cpp
index 32de6c5..a96b863 100644
--- a/src/preferencesdialog.cpp
+++ b/src/preferencesdialog.cpp
@@ -4,6 +4,7 @@
 #include <QHBoxLayout>
 #include <QLabel>
 #include <QComboBox>
+#include <QSpinBox>
 #include <QCheckBox>
 #include <QPushButton>
 #include <QGroupBox>
@@ -32,6 +33,17 @@ PreferencesDialog::PreferencesDialog(QWidget *parent)
     bgColorLayout->addStretch();
 
     groupLayout->addLayout(bgColorLayout);
+
+    QHBoxLayout *cacheSizeLayout = new QHBoxLayout;
+    QLabel *cacheSizeLabel = new QLabel("Folder thumbnail cache (folders):");
+    m_cacheSizeSpinBox = new QSpinBox;
+    m_cacheSizeSpinBox->setRange(1, 20);
+    m_cacheSizeSpinBox->setValue(4);
+    cacheSizeLayout->addWidget(cacheSizeLabel);
+    cacheSizeLayout->addWidget(m_cacheSizeSpinBox);
+    cacheSizeLayout->addStretch();
+    groupLayout->addLayout(cacheSizeLayout);
+
     mainLayout->addWidget(imageGroup);
 
     QGroupBox *layoutGroup = new QGroupBox("Layout", this);
@@ -76,6 +88,16 @@ void PreferencesDialog::setBackgroundColor(const QString &color)
         m_backgroundColorCombo->setCurrentIndex(index);
 }
 
+int PreferencesDialog::getCacheSize() const
+{
+    return m_cacheSizeSpinBox->value();
+}
+
+void PreferencesDialog::setCacheSize(int n)
+{
+    m_cacheSizeSpinBox->setValue(n);
+}
+
 bool PreferencesDialog::getLockDocking() const
 {
     return m_lockDockingCheck->isChecked();
diff --git a/src/preferencesdialog.h b/src/preferencesdialog.h
index 391fc8d..a6b79cf 100644
--- a/src/preferencesdialog.h
+++ b/src/preferencesdialog.h
@@ -4,6 +4,7 @@
 
 class QComboBox;
 class QCheckBox;
+class QSpinBox;
 
 class PreferencesDialog : public QDialog
 {
@@ -15,6 +16,9 @@ public:
     QString getBackgroundColor() const;
     void setBackgroundColor(const QString &color);
 
+    int getCacheSize() const;
+    void setCacheSize(int n);
+
     bool getLockDocking() const;
     void setLockDocking(bool lock);
 
@@ -26,6 +30,7 @@ signals:
 
 private:
     QComboBox *m_backgroundColorCombo;
+    QSpinBox  *m_cacheSizeSpinBox;
     QCheckBox *m_lockDockingCheck;
     QCheckBox *m_resetLayoutCheck;
 };