diff --git a/effects/wobblywindows/wobblywindows.h b/effects/wobblywindows/wobblywindows.h
--- a/effects/wobblywindows/wobblywindows.h
+++ b/effects/wobblywindows/wobblywindows.h
@@ -139,7 +139,6 @@
     void cancelWindowGrab(KWin::EffectWindow *w, int grabRole);
     void startMovedResized(EffectWindow* w);
     void stepMovedResized(EffectWindow* w);
-    bool updateWindowWobblyDatas(EffectWindow* w, qreal time);
 
     struct WindowWobblyInfos {
         Pair* origin;
@@ -171,6 +170,19 @@
         QRect resize_original_rect;
     };
 
+    bool updateWindowWobblyDatas(WindowWobblyInfos& wwi, const QRectF& rect, qreal time);
+
+    void initWobblyInfo(WindowWobblyInfos& wwi, const QRectF& geometry) const;
+    void freeWobblyInfo(WindowWobblyInfos& wwi) const;
+    void wobblyOpenInit(WindowWobblyInfos& wwi) const;
+    void wobblyCloseInit(WindowWobblyInfos& wwi, EffectWindow* w) const;
+
+    WobblyWindowsEffect::Pair computeBezierPoint(const WindowWobblyInfos& wwi, const Pair& point) const;
+
+    static void heightRingLinearMean(Pair** data_pointer, WindowWobblyInfos& wwi);
+
+    void setParameterSet(const ParameterSet& pset);
+
     QHash< const EffectWindow*,  WindowWobblyInfos > windows;
 
     QRegion m_updateRegion;
@@ -198,17 +210,6 @@
 
     bool m_moveWobble; // Expands m_moveEffectEnabled
     bool m_resizeWobble;
-
-    void initWobblyInfo(WindowWobblyInfos& wwi, QRect geometry) const;
-    void freeWobblyInfo(WindowWobblyInfos& wwi) const;
-    void wobblyOpenInit(WindowWobblyInfos& wwi) const;
-    void wobblyCloseInit(WindowWobblyInfos& wwi, EffectWindow* w) const;
-
-    WobblyWindowsEffect::Pair computeBezierPoint(const WindowWobblyInfos& wwi, Pair point) const;
-
-    static void heightRingLinearMean(Pair** data_pointer, WindowWobblyInfos& wwi);
-
-    void setParameterSet(const ParameterSet& pset);
 };
 
 } // namespace KWin
diff --git a/effects/wobblywindows/wobblywindows.cpp b/effects/wobblywindows/wobblywindows.cpp
--- a/effects/wobblywindows/wobblywindows.cpp
+++ b/effects/wobblywindows/wobblywindows.cpp
@@ -57,93 +57,85 @@
     bool closeEffectEnabled;
 };
 
-static const ParameterSet set_0 = {
-    0.15,
-    0.80,
-    0.10,
-    20.0,
-    20.0,
-    0.0,
-    1000.0,
-    0.5,
-    0.0,
-    1000.0,
-    0.5,
-    true,
-    false,
-    false
-};
-
-static const ParameterSet set_1 = {
-    0.10,
-    0.85,
-    0.10,
-    20.0,
-    20.0,
-    0.0,
-    1000.0,
-    0.5,
-    0.0,
-    1000.0,
-    0.5,
-    true,
-    false,
-    false
-};
-
-static const ParameterSet set_2 = {
-    0.06,
-    0.90,
-    0.10,
-    20.0,
-    20.0,
-    0.0,
-    1000.0,
-    0.5,
-    0.0,
-    1000.0,
-    0.5,
-    true,
-    false,
-    false
-};
-
-static const ParameterSet set_3 = {
-    0.03,
-    0.92,
-    0.20,
-    20.0,
-    20.0,
-    0.0,
-    1000.0,
-    0.5,
-    0.0,
-    1000.0,
-    0.5,
-    true,
-    false,
-    false
-};
-
-static const ParameterSet set_4 = {
-    0.01,
-    0.97,
-    0.25,
-    20.0,
-    20.0,
-    0.0,
-    1000.0,
-    0.5,
-    0.0,
-    1000.0,
-    0.5,
-    true,
-    false,
-    false
+static const ParameterSet pset[] = {
+    {
+        0.15,
+        0.80,
+        0.10,
+        20.0,
+        20.0,
+        0.0,
+        1000.0,
+        0.5,
+        0.0,
+        1000.0,
+        0.5,
+        true,
+        false,
+        false
+},  {
+        0.10,
+        0.85,
+        0.10,
+        20.0,
+        20.0,
+        0.0,
+        1000.0,
+        0.5,
+        0.0,
+        1000.0,
+        0.5,
+        true,
+        false,
+        false
+},  {
+        0.06,
+        0.90,
+        0.10,
+        20.0,
+        20.0,
+        0.0,
+        1000.0,
+        0.5,
+        0.0,
+        1000.0,
+        0.5,
+        true,
+        false,
+        false
+},  {
+        0.03,
+        0.92,
+        0.20,
+        20.0,
+        20.0,
+        0.0,
+        1000.0,
+        0.5,
+        0.0,
+        1000.0,
+        0.5,
+        true,
+        false,
+        false
+},  {
+        0.01,
+        0.97,
+        0.25,
+        20.0,
+        20.0,
+        0.0,
+        1000.0,
+        0.5,
+        0.0,
+        1000.0,
+        0.5,
+        true,
+        false,
+        false
+}
 };
 
-static const ParameterSet pset[5] = { set_0, set_1, set_2, set_3, set_4 };
-
 WobblyWindowsEffect::WobblyWindowsEffect()
 {
     initConfig<WobblyWindowsConfig>();
@@ -274,30 +266,34 @@
     // We need to mark the screen windows as transformed. Otherwise the whole
     // screen won't be repainted, resulting in artefacts.
     // Could we just set a subset of the screen to be repainted ?
-    if (windows.count() != 0) {
-        m_updateRegion = QRegion();
-    }
-
+    m_updateRegion = QRegion();
     effects->prePaintScreen(data, time);
 }
 const qreal maxTime = 10.0;
 void WobblyWindowsEffect::prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time)
 {
-    if (windows.contains(w)) {
+    auto it = windows.find(w);
+    if (it != windows.end()) {
         data.setTransformed();
         data.quads = data.quads.makeRegularGrid(m_xTesselation, m_yTesselation);
         bool stop = false;
         qreal updateTime = time;
+        const QRectF rect = w->geometry();
+        WindowWobblyInfos& wwi = it.value();
 
-        while (!stop && (updateTime > maxTime)) {
+        while (!stop && updateTime > 0) {
 #if defined VERBOSE_MODE
             qCDebug(KWINEFFECTS) << "loop time " << updateTime << " / " << time;
 #endif
-            stop = !updateWindowWobblyDatas(w, maxTime);
+            stop = !updateWindowWobblyDatas(wwi, rect, maxTime);
             updateTime -= maxTime;
         }
-        if (!stop && updateTime > 0) {
-            updateWindowWobblyDatas(w, updateTime);
+        if (stop) {
+            if (wwi.status == Closing) {
+                w->unrefWindow();
+            }
+            freeWobblyInfo(wwi);
+            windows.erase(it);
         }
     }
 
@@ -306,8 +302,9 @@
 
 void WobblyWindowsEffect::paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data)
 {
-    if (!(mask & PAINT_SCREEN_TRANSFORMED) && windows.contains(w)) {
-        WindowWobblyInfos& wwi = windows[w];
+    QHash< const EffectWindow*,  WindowWobblyInfos >::const_iterator it;
+    if (!(mask & PAINT_SCREEN_TRANSFORMED) && (it = windows.find(w)) != windows.end()) {
+        const WindowWobblyInfos& wwi = it.value();
         int tx = w->geometry().x();
         int ty = w->geometry().y();
         double left = 0.0;
@@ -336,10 +333,7 @@
 
 void WobblyWindowsEffect::postPaintScreen()
 {
-    if (!windows.isEmpty()) {
-        effects->addRepaint(m_updateRegion);
-    }
-
+    effects->addRepaint(m_updateRegion);
     // Call the next effect.
     effects->postPaintScreen();
 }
@@ -357,8 +351,9 @@
 void WobblyWindowsEffect::slotWindowStepUserMovedResized(EffectWindow *w, const QRect &geometry)
 {
     Q_UNUSED(geometry)
-    if (windows.contains(w)) {
-        WindowWobblyInfos& wwi = windows[w];
+    auto it = windows.find(w);
+    if (it != windows.end()) {
+        WindowWobblyInfos& wwi = it.value();
         QRect rect = w->geometry();
         if (rect.y() != wwi.resize_original_rect.y()) wwi.can_wobble_top = true;
         if (rect.x() != wwi.resize_original_rect.x()) wwi.can_wobble_left = true;
@@ -369,8 +364,9 @@
 
 void WobblyWindowsEffect::slotWindowFinishUserMovedResized(EffectWindow *w)
 {
-    if (windows.contains(w)) {
-        WindowWobblyInfos& wwi = windows[w];
+    auto it = windows.find(w);
+    if (it != windows.end()) {
+        WindowWobblyInfos& wwi = it.value();
         wwi.status = Free;
         QRect rect = w->geometry();
         if (rect.y() != wwi.resize_original_rect.y()) wwi.can_wobble_top = true;
@@ -391,8 +387,9 @@
         stepMovedResized(w);
     }
 
-    if (windows.contains(w)) {
-        WindowWobblyInfos& wwi = windows[w];
+    auto it = windows.find(w);
+    if (it != windows.end()) {
+        WindowWobblyInfos& wwi = it.value();
         QRect rect = w->geometry();
         if (rect.y() != wwi.resize_original_rect.y()) wwi.can_wobble_top = true;
         if (rect.x() != wwi.resize_original_rect.x()) wwi.can_wobble_left = true;
@@ -403,13 +400,14 @@
 
 void WobblyWindowsEffect::startMovedResized(EffectWindow* w)
 {
-    if (!windows.contains(w)) {
+    auto it = windows.find(w);
+    if (it == windows.end()) {
         WindowWobblyInfos new_wwi;
         initWobblyInfo(new_wwi, w->geometry());
-        windows[w] = new_wwi;
+        it = windows.insert(w, new_wwi);
     }
 
-    WindowWobblyInfos& wwi = windows[w];
+    WindowWobblyInfos& wwi = it.value();
     wwi.status = Moving;
     const QRectF& rect = w->geometry();
 
@@ -445,13 +443,14 @@
 void WobblyWindowsEffect::stepMovedResized(EffectWindow* w)
 {
     QRect new_geometry = w->geometry();
-    if (!windows.contains(w)) {
+    auto it = windows.find(w);
+    if (it == windows.end()) {
         WindowWobblyInfos new_wwi;
         initWobblyInfo(new_wwi, new_geometry);
-        windows[w] = new_wwi;
+        it = windows.insert(w, new_wwi);
     }
 
-    WindowWobblyInfos& wwi = windows[w];
+    WindowWobblyInfos& wwi = it.value();
     wwi.status = Free;
 
     QRect maximized_area = effects->clientArea(MaximizeArea, w);
@@ -476,37 +475,38 @@
 void WobblyWindowsEffect::slotWindowAdded(EffectWindow* w)
 {
     if (m_openEffectEnabled && w->data(WindowAddedGrabRole).value<void*>() == nullptr) {
-        if (windows.contains(w)) {
+        auto it = windows.find(w);
+        if (it != windows.end()) {
             // could this happen ??
-            WindowWobblyInfos& wwi = windows[w];
+            WindowWobblyInfos& wwi = it.value();
             wobblyOpenInit(wwi);
         } else {
             WindowWobblyInfos new_wwi;
             initWobblyInfo(new_wwi, w->geometry());
             wobblyOpenInit(new_wwi);
-            windows[w] = new_wwi;
+            windows.insert(w, new_wwi);
         }
     }
 }
 
 void WobblyWindowsEffect::slotWindowClosed(EffectWindow* w)
 {
-    if (windows.contains(w)) {
-        WindowWobblyInfos& wwi = windows[w];
+    auto it = windows.find(w);
+    if (it != windows.end()) {
+        WindowWobblyInfos& wwi = it.value();
         if (m_closeEffectEnabled) {
             wobblyCloseInit(wwi, w);
             w->refWindow();
         } else {
             freeWobblyInfo(wwi);
-            windows.remove(w);
-            if (windows.isEmpty())
-                effects->addRepaintFull();
+            windows.erase(it);
+            w->unrefWindow();
         }
     } else if (m_closeEffectEnabled  && w->data(WindowClosedGrabRole).value<void*>() == nullptr) {
         WindowWobblyInfos new_wwi;
         initWobblyInfo(new_wwi, w->geometry());
         wobblyCloseInit(new_wwi, w);
-        windows[w] = new_wwi;
+        windows.insert(w, new_wwi);
         w->refWindow();
     }
 }
@@ -547,7 +547,7 @@
     wwi.status = Closing;
 }
 
-void WobblyWindowsEffect::initWobblyInfo(WindowWobblyInfos& wwi, QRect geometry) const
+void WobblyWindowsEffect::initWobblyInfo(WindowWobblyInfos& wwi, const QRectF& geometry) const
 {
     wwi.count = 4 * 4;
     wwi.width = 4;
@@ -614,11 +614,11 @@
     delete[] wwi.bezierSurface;
 }
 
-WobblyWindowsEffect::Pair WobblyWindowsEffect::computeBezierPoint(const WindowWobblyInfos& wwi, Pair point) const
+WobblyWindowsEffect::Pair WobblyWindowsEffect::computeBezierPoint(const WindowWobblyInfos& wwi, const Pair& point) const
 {
     // compute the input value
-    Pair topleft = wwi.origin[0];
-    Pair bottomright = wwi.origin[wwi.count-1];
+    const Pair& topleft = wwi.origin[0];
+    const Pair& bottomright = wwi.origin[wwi.count-1];
 
 //    ASSERT1(point.x >= topleft.x);
 //    ASSERT1(point.y >= topleft.y);
@@ -704,15 +704,8 @@
 
 } // close the anonymous namespace
 
-bool WobblyWindowsEffect::updateWindowWobblyDatas(EffectWindow* w, qreal time)
+bool WobblyWindowsEffect::updateWindowWobblyDatas(WindowWobblyInfos& wwi, const QRectF& rect, qreal time)
 {
-    QRectF rect = w->geometry();
-    WindowWobblyInfos& wwi = windows[w];
-
-    if (wwi.status == Closing) {
-        rect = wwi.closeRect;
-    }
-
     qreal x_length = rect.width() / (wwi.width - 1.0);
     qreal y_length = rect.height() / (wwi.height - 1.0);
 
@@ -753,13 +746,13 @@
     // top-left
 
     if (wwi.constraint[0]) {
-        Pair window_pos = wwi.origin[0];
-        Pair current_pos = wwi.position[0];
+        const Pair& window_pos = wwi.origin[0];
+        const Pair& current_pos = wwi.position[0];
         Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
         Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
         wwi.acceleration[0] = accel;
     } else {
-        Pair& pos = wwi.position[0];
+        const Pair& pos = wwi.position[0];
         neibourgs[0] = wwi.position[1];
         neibourgs[1] = wwi.position[wwi.width];
 
@@ -775,13 +768,13 @@
     // top-right
 
     if (wwi.constraint[wwi.width-1]) {
-        Pair window_pos = wwi.origin[wwi.width-1];
-        Pair current_pos = wwi.position[wwi.width-1];
+        const Pair& window_pos = wwi.origin[wwi.width-1];
+        const Pair& current_pos = wwi.position[wwi.width-1];
         Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
         Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
         wwi.acceleration[wwi.width-1] = accel;
     } else {
-        Pair& pos = wwi.position[wwi.width-1];
+        const Pair& pos = wwi.position[wwi.width-1];
         neibourgs[0] = wwi.position[wwi.width-2];
         neibourgs[1] = wwi.position[2*wwi.width-1];
 
@@ -797,13 +790,13 @@
     // bottom-left
 
     if (wwi.constraint[wwi.width*(wwi.height-1)]) {
-        Pair window_pos = wwi.origin[wwi.width*(wwi.height-1)];
-        Pair current_pos = wwi.position[wwi.width*(wwi.height-1)];
+        const Pair& window_pos = wwi.origin[wwi.width*(wwi.height-1)];
+        const Pair& current_pos = wwi.position[wwi.width*(wwi.height-1)];
         Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
         Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
         wwi.acceleration[wwi.width*(wwi.height-1)] = accel;
     } else {
-        Pair& pos = wwi.position[wwi.width*(wwi.height-1)];
+        const Pair& pos = wwi.position[wwi.width*(wwi.height-1)];
         neibourgs[0] = wwi.position[wwi.width*(wwi.height-1)+1];
         neibourgs[1] = wwi.position[wwi.width*(wwi.height-2)];
 
@@ -819,13 +812,13 @@
     // bottom-right
 
     if (wwi.constraint[wwi.count-1]) {
-        Pair window_pos = wwi.origin[wwi.count-1];
-        Pair current_pos = wwi.position[wwi.count-1];
+        const Pair& window_pos = wwi.origin[wwi.count-1];
+        const Pair& current_pos = wwi.position[wwi.count-1];
         Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
         Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
         wwi.acceleration[wwi.count-1] = accel;
     } else {
-        Pair& pos = wwi.position[wwi.count-1];
+        const Pair& pos = wwi.position[wwi.count-1];
         neibourgs[0] = wwi.position[wwi.count-2];
         neibourgs[1] = wwi.position[wwi.width*(wwi.height-1)-1];
 
@@ -844,13 +837,13 @@
     // top border
     for (unsigned int i = 1; i < wwi.width - 1; ++i) {
         if (wwi.constraint[i]) {
-            Pair window_pos = wwi.origin[i];
-            Pair current_pos = wwi.position[i];
+            const Pair& window_pos = wwi.origin[i];
+            const Pair& current_pos = wwi.position[i];
             Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
             Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
             wwi.acceleration[i] = accel;
         } else {
-            Pair& pos = wwi.position[i];
+            const Pair& pos = wwi.position[i];
             neibourgs[0] = wwi.position[i-1];
             neibourgs[1] = wwi.position[i+1];
             neibourgs[2] = wwi.position[i+wwi.width];
@@ -868,13 +861,13 @@
     // bottom border
     for (unsigned int i = wwi.width * (wwi.height - 1) + 1; i < wwi.count - 1; ++i) {
         if (wwi.constraint[i]) {
-            Pair window_pos = wwi.origin[i];
-            Pair current_pos = wwi.position[i];
+            const Pair& window_pos = wwi.origin[i];
+            const Pair& current_pos = wwi.position[i];
             Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
             Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
             wwi.acceleration[i] = accel;
         } else {
-            Pair& pos = wwi.position[i];
+            const Pair& pos = wwi.position[i];
             neibourgs[0] = wwi.position[i-1];
             neibourgs[1] = wwi.position[i+1];
             neibourgs[2] = wwi.position[i-wwi.width];
@@ -892,13 +885,13 @@
     // left border
     for (unsigned int i = wwi.width; i < wwi.width*(wwi.height - 1); i += wwi.width) {
         if (wwi.constraint[i]) {
-            Pair window_pos = wwi.origin[i];
-            Pair current_pos = wwi.position[i];
+            const Pair& window_pos = wwi.origin[i];
+            const Pair& current_pos = wwi.position[i];
             Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
             Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
             wwi.acceleration[i] = accel;
         } else {
-            Pair& pos = wwi.position[i];
+            const Pair& pos = wwi.position[i];
             neibourgs[0] = wwi.position[i+1];
             neibourgs[1] = wwi.position[i-wwi.width];
             neibourgs[2] = wwi.position[i+wwi.width];
@@ -916,13 +909,13 @@
     // right border
     for (unsigned int i = 2 * wwi.width - 1; i < wwi.count - 1; i += wwi.width) {
         if (wwi.constraint[i]) {
-            Pair window_pos = wwi.origin[i];
-            Pair current_pos = wwi.position[i];
+            const Pair& window_pos = wwi.origin[i];
+            const Pair& current_pos = wwi.position[i];
             Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
             Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
             wwi.acceleration[i] = accel;
         } else {
-            Pair& pos = wwi.position[i];
+            const Pair& pos = wwi.position[i];
             neibourgs[0] = wwi.position[i-1];
             neibourgs[1] = wwi.position[i-wwi.width];
             neibourgs[2] = wwi.position[i+wwi.width];
@@ -943,13 +936,13 @@
             unsigned int index = i + j * wwi.width;
 
             if (wwi.constraint[index]) {
-                Pair window_pos = wwi.origin[index];
-                Pair current_pos = wwi.position[index];
+                const Pair& window_pos = wwi.origin[index];
+                const Pair& current_pos = wwi.position[index];
                 Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
                 Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
                 wwi.acceleration[index] = accel;
             } else {
-                Pair& pos = wwi.position[index];
+                const Pair& pos = wwi.position[index];
                 neibourgs[0] = wwi.position[index-1];
                 neibourgs[1] = wwi.position[index+1];
                 neibourgs[2] = wwi.position[index-wwi.width];
@@ -1049,13 +1042,6 @@
 #endif
 
     if (wwi.status != Moving && acc_sum < m_stopAcceleration && vel_sum < m_stopVelocity) {
-        if (wwi.status == Closing) {
-            w->unrefWindow();
-        }
-        freeWobblyInfo(wwi);
-        windows.remove(w);
-        if (windows.isEmpty())
-            effects->addRepaintFull();
         return false;
     }
 
@@ -1072,7 +1058,7 @@
     // top-left
     {
         Pair& res = wwi.buffer[0];
-        Pair vit = data[0];
+        const Pair& vit = data[0];
         neibourgs[0] = data[1];
         neibourgs[1] = data[wwi.width];
         neibourgs[2] = data[wwi.width+1];
@@ -1085,7 +1071,7 @@
     // top-right
     {
         Pair& res = wwi.buffer[wwi.width-1];
-        Pair vit = data[wwi.width-1];
+        const Pair& vit = data[wwi.width-1];
         neibourgs[0] = data[wwi.width-2];
         neibourgs[1] = data[2*wwi.width-1];
         neibourgs[2] = data[2*wwi.width-2];
@@ -1098,7 +1084,7 @@
     // bottom-left
     {
         Pair& res = wwi.buffer[wwi.width*(wwi.height-1)];
-        Pair vit = data[wwi.width*(wwi.height-1)];
+        const Pair& vit = data[wwi.width*(wwi.height-1)];
         neibourgs[0] = data[wwi.width*(wwi.height-1)+1];
         neibourgs[1] = data[wwi.width*(wwi.height-2)];
         neibourgs[2] = data[wwi.width*(wwi.height-2)+1];
@@ -1111,7 +1097,7 @@
     // bottom-right
     {
         Pair& res = wwi.buffer[wwi.count-1];
-        Pair vit = data[wwi.count-1];
+        const Pair& vit = data[wwi.count-1];
         neibourgs[0] = data[wwi.count-2];
         neibourgs[1] = data[wwi.width*(wwi.height-1)-1];
         neibourgs[2] = data[wwi.width*(wwi.height-1)-2];
@@ -1126,7 +1112,7 @@
     // top border
     for (unsigned int i = 1; i < wwi.width - 1; ++i) {
         Pair& res = wwi.buffer[i];
-        Pair vit = data[i];
+        const Pair& vit = data[i];
         neibourgs[0] = data[i-1];
         neibourgs[1] = data[i+1];
         neibourgs[2] = data[i+wwi.width];
@@ -1140,7 +1126,7 @@
     // bottom border
     for (unsigned int i = wwi.width * (wwi.height - 1) + 1; i < wwi.count - 1; ++i) {
         Pair& res = wwi.buffer[i];
-        Pair vit = data[i];
+        const Pair& vit = data[i];
         neibourgs[0] = data[i-1];
         neibourgs[1] = data[i+1];
         neibourgs[2] = data[i-wwi.width];
@@ -1154,7 +1140,7 @@
     // left border
     for (unsigned int i = wwi.width; i < wwi.width*(wwi.height - 1); i += wwi.width) {
         Pair& res = wwi.buffer[i];
-        Pair vit = data[i];
+        const Pair& vit = data[i];
         neibourgs[0] = data[i+1];
         neibourgs[1] = data[i-wwi.width];
         neibourgs[2] = data[i+wwi.width];
@@ -1168,7 +1154,7 @@
     // right border
     for (unsigned int i = 2 * wwi.width - 1; i < wwi.count - 1; i += wwi.width) {
         Pair& res = wwi.buffer[i];
-        Pair vit = data[i];
+        const Pair& vit = data[i];
         neibourgs[0] = data[i-1];
         neibourgs[1] = data[i-wwi.width];
         neibourgs[2] = data[i+wwi.width];
@@ -1185,7 +1171,7 @@
             unsigned int index = i + j * wwi.width;
 
             Pair& res = wwi.buffer[index];
-            Pair& vit = data[index];
+            const Pair& vit = data[index];
             neibourgs[0] = data[index-1];
             neibourgs[1] = data[index+1];
             neibourgs[2] = data[index-wwi.width];