diff --git a/src/app/tools/tool_loop.h b/src/app/tools/tool_loop.h
index c08360fe6..b71327cef 100644
--- a/src/app/tools/tool_loop.h
+++ b/src/app/tools/tool_loop.h
@@ -222,6 +222,8 @@ namespace app {
       // Returns true if the loop was canceled by the user
       virtual bool isCanceled() = 0;
 
+      virtual void limitDirtyAreaToViewport(gfx::Region& rgn) = 0;
+
       // Redraws the dirty area.
       virtual void updateDirtyArea(const gfx::Region& dirtyArea) = 0;
 
diff --git a/src/app/tools/tool_loop_manager.cpp b/src/app/tools/tool_loop_manager.cpp
index ed1fe1822..8a0db5948 100644
--- a/src/app/tools/tool_loop_manager.cpp
+++ b/src/app/tools/tool_loop_manager.cpp
@@ -111,7 +111,8 @@ bool ToolLoopManager::releaseButton(const Pointer& pointer)
 
   bool res = m_toolLoop->getController()->releaseButton(m_stroke, spritePoint);
 
-  if (!res && (m_toolLoop->getInk()->isSelection() ||
+  if (!res && (m_toolLoop->getTracePolicy() == TracePolicy::Last ||
+               m_toolLoop->getInk()->isSelection() ||
                m_toolLoop->getInk()->isSlice() ||
                m_toolLoop->getFilled())) {
     m_toolLoop->getInk()->setFinalStep(m_toolLoop, true);
@@ -165,6 +166,13 @@ void ToolLoopManager::doLoopStep(bool lastStep)
 
   calculateDirtyArea(strokes);
 
+  // If we are not in the last step (when the mouse button is
+  // released) we are only showing a preview of the tool, so we can
+  // limit the dirty area to the visible viewport bounds. In this way
+  // the area using in validateoDstImage() can be a lot smaller.
+  if (m_toolLoop->getTracePolicy() == TracePolicy::Last && !lastStep)
+    m_toolLoop->limitDirtyAreaToViewport(m_dirtyArea);
+
   // Validate source image area.
   if (m_toolLoop->getInk()->needsSpecialSourceArea()) {
     gfx::Region srcArea;
@@ -177,10 +185,10 @@ void ToolLoopManager::doLoopStep(bool lastStep)
 
   m_toolLoop->getInk()->prepareForStrokes(m_toolLoop, strokes);
 
-  // Invalidate destionation image areas.
+  // Invalidate destination image area.
   if (m_toolLoop->getTracePolicy() == TracePolicy::Last) {
     // Copy source to destination (reset the previous trace). Useful
-    // for tools like Line and Ellipse (we kept the last trace only).
+    // for tools like Line and Ellipse (we keep the last trace only).
     m_toolLoop->invalidateDstImage();
   }
   else if (m_toolLoop->getTracePolicy() == TracePolicy::AccumulateUpdateLast) {
diff --git a/src/app/ui/editor/tool_loop_impl.cpp b/src/app/ui/editor/tool_loop_impl.cpp
index 75156f8cf..45bacae93 100644
--- a/src/app/ui/editor/tool_loop_impl.cpp
+++ b/src/app/ui/editor/tool_loop_impl.cpp
@@ -260,6 +260,10 @@ public:
   tools::Symmetry* getSymmetry() override { return m_symmetry.get(); }
   doc::Remap* getShadingRemap() override { return m_shadingRemap.get(); }
 
+  void limitDirtyAreaToViewport(gfx::Region& rgn) override {
+    rgn &= gfx::Region(m_editor->getVisibleSpriteBounds().inflate(1, 1));
+  }
+
   void updateDirtyArea(const gfx::Region& dirtyArea) override {
     // This is necessary here so the "on sprite crosshair" is hidden,
     // we update screen pixels with the new sprite, and then we show