diff --git a/Kernel/Process.h b/Kernel/Process.h
index eddd71ba29..865a6b5684 100644
--- a/Kernel/Process.h
+++ b/Kernel/Process.h
@@ -195,7 +195,7 @@ public:
     int gui$create_window(const GUI_CreateWindowParameters*);
     int gui$destroy_window(int window_id);
     int gui$get_window_backing_store(int window_id, GUI_WindowBackingStoreInfo*);
-    int gui$invalidate_window(int window_id);
+    int gui$invalidate_window(int window_id, const GUI_Rect*);
 
     DisplayInfo get_display_info();
 
diff --git a/Kernel/ProcessGUI.cpp b/Kernel/ProcessGUI.cpp
index bdd0636ba1..417dac360e 100644
--- a/Kernel/ProcessGUI.cpp
+++ b/Kernel/ProcessGUI.cpp
@@ -99,16 +99,21 @@ int Process::gui$get_window_backing_store(int window_id, GUI_WindowBackingStoreI
     return 0;
 }
 
-int Process::gui$invalidate_window(int window_id)
+int Process::gui$invalidate_window(int window_id, const GUI_Rect* rect)
 {
     dbgprintf("%s<%u> gui$invalidate_window (window_id=%d)\n", name().characters(), pid(), window_id);
     if (window_id < 0)
         return -EINVAL;
+    if (rect && !validate_read_typed(rect))
+        return -EFAULT;
     auto it = m_windows.find(window_id);
     if (it == m_windows.end())
         return -EBADWINDOW;
     auto& window = *(*it).value;
-    WSEventLoop::the().post_event(&window, make<WSEvent>(WSEvent::WM_Invalidate));
+    auto event = make<WSEvent>(WSEvent::WM_Invalidate);
+    if (rect)
+        event->set_rect(*rect);
+    WSEventLoop::the().post_event(&window, move(event));
     WSEventLoop::the().server_process().request_wakeup();
     return 0;
 }
diff --git a/Kernel/Syscall.cpp b/Kernel/Syscall.cpp
index a4d9c0e9de..038ebc4318 100644
--- a/Kernel/Syscall.cpp
+++ b/Kernel/Syscall.cpp
@@ -198,7 +198,7 @@ static dword handle(RegisterDump& regs, dword function, dword arg1, dword arg2,
     case Syscall::SC_gui_get_window_backing_store:
         return current->gui$get_window_backing_store((int)arg1, (GUI_WindowBackingStoreInfo*)arg2);
     case Syscall::SC_gui_invalidate_window:
-        return current->gui$invalidate_window((int)arg1);
+        return current->gui$invalidate_window((int)arg1, (const GUI_Rect*)arg2);
     default:
         kprintf("<%u> int0x80: Unknown function %u requested {%x, %x, %x}\n", current->pid(), function, arg1, arg2, arg3);
         break;
diff --git a/LibC/gui.cpp b/LibC/gui.cpp
index fd4b75dfc4..2c11bcb8c8 100644
--- a/LibC/gui.cpp
+++ b/LibC/gui.cpp
@@ -9,9 +9,9 @@ int gui_create_window(const GUI_CreateWindowParameters* params)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
-int gui_invalidate_window(int window_id)
+int gui_invalidate_window(int window_id, const GUI_Rect* rect)
 {
-    int rc = syscall(SC_gui_invalidate_window, window_id);
+    int rc = syscall(SC_gui_invalidate_window, window_id, rect);
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
diff --git a/LibC/gui.h b/LibC/gui.h
index fe7f1134b5..e92809fe4a 100644
--- a/LibC/gui.h
+++ b/LibC/gui.h
@@ -6,7 +6,7 @@
 __BEGIN_DECLS
 
 int gui_create_window(const GUI_CreateWindowParameters* params);
-int gui_invalidate_window(int window_id);
+int gui_invalidate_window(int window_id, const GUI_Rect*);
 int gui_get_window_backing_store(int window_id, GUI_WindowBackingStoreInfo* info);
 
 __END_DECLS
diff --git a/Terminal/Terminal.cpp b/Terminal/Terminal.cpp
index 0b893f05a6..8c2aeab0d7 100644
--- a/Terminal/Terminal.cpp
+++ b/Terminal/Terminal.cpp
@@ -49,6 +49,7 @@ Terminal::Terminal()
     // Rightmost column is always last tab on line.
     m_horizontal_tabs[columns() - 1] = 1;
 
+    m_row_needs_invalidation = (bool*)(malloc(rows() * sizeof(bool)));
     m_buffer = (byte*)malloc(rows() * columns());
     m_attributes = (Attribute*)malloc(rows() * columns() * sizeof(Attribute));
     memset(m_buffer, ' ', m_rows * m_columns);
@@ -58,6 +59,7 @@ Terminal::Terminal()
 
 Terminal::~Terminal()
 {
+    free(m_row_needs_invalidation);
     free(m_buffer);
     free(m_attributes);
     free(m_horizontal_tabs);
@@ -408,6 +410,12 @@ Rect Terminal::glyph_rect(word row, word column)
     return { x + m_inset, y + m_inset, font().glyph_width(), font().glyph_height() };
 }
 
+Rect Terminal::row_rect(word row)
+{
+    int y = row * m_line_height;
+    return { m_inset, y + m_inset, font().glyph_width() * m_columns, font().glyph_height() };
+}
+
 inline Terminal::Attribute& Terminal::attribute_at(word row, word column)
 {
     return m_attributes[(row * m_columns) + column];
@@ -417,6 +425,10 @@ void Terminal::paint()
 {
     Rect rect { 0, 0, m_pixel_width, m_pixel_height };
     Painter painter(*m_backing);
+
+    bool need_full_invalidation = false;
+    memset(m_row_needs_invalidation, 0, rows() * sizeof(bool));
+
 #ifdef FAST_SCROLL
     if (m_rows_to_scroll_backing_store && m_rows_to_scroll_backing_store < m_rows) {
         int first_scanline = m_inset;
@@ -428,6 +440,7 @@ void Terminal::paint()
             m_backing->scanline(second_scanline),
             scanlines_to_copy * m_pixel_width
         );
+        need_full_invalidation = true;
         attribute_at(m_cursor_row - m_rows_to_scroll_backing_store, m_cursor_column).dirty = true;
     }
     m_rows_to_scroll_backing_store = 0;
@@ -439,6 +452,7 @@ void Terminal::paint()
             if (!attribute.dirty)
                 continue;
             attribute.dirty = false;
+            m_row_needs_invalidation[row] = true;
             char ch = m_buffer[(row * m_columns) + (column)];
             auto character_rect = glyph_rect(row, column);
             auto character_background = ansi_color(attribute.background_color);
@@ -455,10 +469,30 @@ void Terminal::paint()
     else
         painter.draw_rect(cursor_rect, Color::MidGray);
 
-    if (m_belling)
-        painter.draw_rect(rect, Color::Red);
+    m_row_needs_invalidation[m_cursor_row] = true;
 
-    int rc = gui_invalidate_window(m_window_id);
+    if (m_belling) {
+        need_full_invalidation = true;
+        painter.draw_rect(rect, Color::Red);
+    }
+
+    if (need_full_invalidation) {
+        invalidate_window();
+        return;
+    }
+
+    Rect invalidation_rect;
+    for (int i = 0; i < m_rows; ++i) {
+        if (m_row_needs_invalidation[i])
+            invalidation_rect = invalidation_rect.united(row_rect(i));
+    }
+    invalidate_window(invalidation_rect);
+}
+
+void Terminal::invalidate_window(const Rect& a_rect)
+{
+    GUI_Rect rect = a_rect;
+    int rc = gui_invalidate_window(m_window_id, a_rect.is_null() ? nullptr : &rect);
     if (rc < 0) {
         perror("gui_invalidate_window");
         exit(1);
diff --git a/Terminal/Terminal.h b/Terminal/Terminal.h
index 4b069b141b..50b6ecf03f 100644
--- a/Terminal/Terminal.h
+++ b/Terminal/Terminal.h
@@ -25,6 +25,7 @@ private:
     void set_cursor(unsigned row, unsigned column);
     void put_character_at(unsigned row, unsigned column, byte ch);
     void invalidate_cursor();
+    void invalidate_window(const Rect& = Rect());
 
     void escape$A(const Vector<unsigned>&);
     void escape$D(const Vector<unsigned>&);
@@ -40,6 +41,7 @@ private:
     word columns() const { return m_columns; }
     word rows() const { return m_rows; }
     Rect glyph_rect(word row, word column);
+    Rect row_rect(word row);
 
     struct Attribute {
         Attribute() { reset(); }
@@ -58,6 +60,7 @@ private:
 
     byte* m_buffer { nullptr };
     Attribute* m_attributes { nullptr };
+    bool* m_row_needs_invalidation { nullptr };
 
     word m_columns { 0 };
     word m_rows { 0 };
diff --git a/Userland/guitest.cpp b/Userland/guitest.cpp
index e538fbf09a..6b2caf0b7c 100644
--- a/Userland/guitest.cpp
+++ b/Userland/guitest.cpp
@@ -43,7 +43,7 @@ int main(int argc, char** argv)
 
     paint(*bitmap, backing.size.width, backing.size.height);
 
-    rc = gui_invalidate_window(window_id);
+    rc = gui_invalidate_window(window_id, nullptr);
     if (rc < 0) {
         perror("gui_invalidate_window");
         return 1;
@@ -69,7 +69,7 @@ int main(int argc, char** argv)
 
         if (event.type == GUI_Event::Type::MouseDown) {
             paint(*bitmap, backing.size.width, backing.size.height);
-            gui_invalidate_window(window_id);
+            gui_invalidate_window(window_id, nullptr);
         }
 
     }
diff --git a/Widgets/Rect.cpp b/Widgets/Rect.cpp
index f07d78e7fe..5b01bf2e1e 100644
--- a/Widgets/Rect.cpp
+++ b/Widgets/Rect.cpp
@@ -22,6 +22,10 @@ void Rect::intersect(const Rect& other)
 
 Rect Rect::united(const Rect& other) const
 {
+    if (is_null())
+        return other;
+    if (other.is_null())
+        return *this;
     Rect rect;
     rect.set_left(min(left(), other.left()));
     rect.set_top(min(top(), other.top()));
diff --git a/Widgets/Rect.h b/Widgets/Rect.h
index aa9b02b536..e99e6d6ded 100644
--- a/Widgets/Rect.h
+++ b/Widgets/Rect.h
@@ -20,9 +20,14 @@ public:
     }
     Rect(const GUI_Rect&);
 
+    bool is_null() const
+    {
+        return width() == 0 && height() == 0;
+    }
+
     bool is_empty() const
     {
-        return width() == 0 || height() == 0;
+        return width() <= 0 || height() <= 0;
     }
 
     void move_by(int dx, int dy)
diff --git a/WindowServer/WSEvent.h b/WindowServer/WSEvent.h
index 702cd32efd..8a3a4ce99d 100644
--- a/WindowServer/WSEvent.h
+++ b/WindowServer/WSEvent.h
@@ -53,8 +53,15 @@ public:
     bool isKeyEvent() const { return m_type == KeyUp || m_type == KeyDown; }
     bool isPaintEvent() const { return m_type == Paint; }
 
+    Rect rect() const { return m_rect; }
+    void set_rect(const GUI_Rect& rect)
+    {
+        m_rect = rect;
+    }
+
 private:
     Type m_type { Invalid };
+    Rect m_rect;
 };
 
 class PaintEvent final : public WSEvent {
diff --git a/WindowServer/WSEventLoop.cpp b/WindowServer/WSEventLoop.cpp
index 37d77fc0b9..7fed463269 100644
--- a/WindowServer/WSEventLoop.cpp
+++ b/WindowServer/WSEventLoop.cpp
@@ -83,7 +83,9 @@ void WSEventLoop::post_event(WSEventReceiver* receiver, OwnPtr<WSEvent>&& event)
 
     if (event->type() == WSEvent::WM_Invalidate) {
         for (auto& queued_event : m_queued_events) {
-            if (receiver == queued_event.receiver && queued_event.event->type() == WSEvent::WM_Invalidate) {
+            if (receiver == queued_event.receiver
+                && queued_event.event->type() == WSEvent::WM_Invalidate
+                && (queued_event.event->rect().is_empty() || queued_event.event->rect().contains(event->rect()))) {
 #ifdef WSEVENTLOOP_DEBUG
                 dbgprintf("Swallow WM_Invalidate\n");
 #endif
diff --git a/WindowServer/WSWindow.cpp b/WindowServer/WSWindow.cpp
index b3e986c301..d18d273d9c 100644
--- a/WindowServer/WSWindow.cpp
+++ b/WindowServer/WSWindow.cpp
@@ -75,7 +75,7 @@ void WSWindow::event(WSEvent& event)
         gui_event.key.character = static_cast<KeyEvent&>(event).text()[0];
         break;
     case WSEvent::WM_Invalidate:
-        WSWindowManager::the().invalidate(*this);
+        WSWindowManager::the().invalidate(*this, event.rect());
         return;
     case WSEvent::WindowActivated:
         gui_event.type = GUI_Event::Type::WindowActivated;
diff --git a/WindowServer/WSWindowManager.cpp b/WindowServer/WSWindowManager.cpp
index 31e8cad249..325863802f 100644
--- a/WindowServer/WSWindowManager.cpp
+++ b/WindowServer/WSWindowManager.cpp
@@ -412,6 +412,21 @@ void WSWindowManager::invalidate(const WSWindow& window)
     invalidate(outerRectForWindow(window.rect()));
 }
 
+void WSWindowManager::invalidate(const WSWindow& window, const Rect& rect)
+{
+    if (rect.is_empty()) {
+        invalidate(window);
+        return;
+    }
+    ASSERT_INTERRUPTS_ENABLED();
+    LOCKER(m_lock);
+    auto outer_rect = outerRectForWindow(window.rect());
+    auto inner_rect = rect;
+    inner_rect.move_by(window.position());
+    inner_rect.intersect(outer_rect);
+    invalidate(inner_rect);
+}
+
 void WSWindowManager::flush(const Rect& a_rect)
 {
     auto rect = Rect::intersection(a_rect, m_screen_rect);
diff --git a/WindowServer/WSWindowManager.h b/WindowServer/WSWindowManager.h
index 4a7d26d246..180a44abe0 100644
--- a/WindowServer/WSWindowManager.h
+++ b/WindowServer/WSWindowManager.h
@@ -34,6 +34,7 @@ public:
     void draw_cursor();
 
     void invalidate(const WSWindow&);
+    void invalidate(const WSWindow&, const Rect&);
     void invalidate(const Rect&);
     void invalidate();
     void flush(const Rect&);