Index: src/backend/worksheet/plots/cartesian/XYCurve.cpp
===================================================================
--- src/backend/worksheet/plots/cartesian/XYCurve.cpp
+++ src/backend/worksheet/plots/cartesian/XYCurve.cpp
@@ -860,6 +860,7 @@
 	bool oldValue = isVisible();
 	setVisible(on);
 	emit q->visibilityChanged(on);
+	retransform();
 	return oldValue;
 }
 
@@ -868,6 +869,10 @@
   Triggers the update of lines, drop lines, symbols etc.
 */
 void XYCurvePrivate::retransform() {
+
+	if (!isVisible())
+		return;
+
 	DEBUG("\nXYCurvePrivate::retransform() name = " << name().toStdString() << ", m_suppressRetransform = " << m_suppressRetransform);
 	DEBUG("	plot = " << plot);
 	if (m_suppressRetransform || !plot)
@@ -902,50 +907,70 @@
 		QApplication::processEvents(QEventLoop::AllEvents, 0);
 	}
 
-	QPointF tempPoint;
+	//take over only valid and non masked points.
+	 // remove points if they are on the same scene coord
+	 {
+		 #if PERFTRACE_CURVES == 1
+			 PERFTRACE(name().toLatin1() + ", XYCurvePrivate::retransform(), remove points");
+		 #endif
+
+	 AbstractColumn::ColumnMode xColMode = xColumn->columnMode();
+	 AbstractColumn::ColumnMode yColMode = yColumn->columnMode();
+	if (xColumn->rowCount() > 0 &&
+		(xColMode == AbstractColumn::ColumnMode::Numeric ||
+		 xColMode == AbstractColumn::ColumnMode::Integer ||
+		 xColMode == AbstractColumn::ColumnMode::DateTime) &&
+		(yColMode == AbstractColumn::ColumnMode::Numeric ||
+		 yColMode == AbstractColumn::ColumnMode::Integer ||
+		 yColMode == AbstractColumn::ColumnMode::DateTime)) {
+
+		QPointF p1= cSystem->mapSceneToLogical(QPointF(1,1));
+		QPointF p2= cSystem->mapSceneToLogical(QPointF(0,0));
+		double dxMinLogical = abs(p1.x()-p2.x());
+		double dyMinLogical = abs(p1.y()-p2.y());
+
+		double xValue;
+		double yValue;
+		if (xColMode == AbstractColumn::DateTime)
+			xValue = xColumn->dateTimeAt(0).toMSecsSinceEpoch();
+		else
+			xValue = xColumn->valueAt(0);
+
+		if (yColMode == AbstractColumn::DateTime)
+			yValue = yColumn->dateTimeAt(0).toMSecsSinceEpoch();
+		else
+			yValue = yColumn->valueAt(0);
+
+		symbolPointsLogical.append(QPointF(xValue, yValue));
+		connectedPointsLogical.push_back(true);
+
+		for (int row = 1; row < xColumn->rowCount(); row++) {
+			if ( xColumn->isValid(row) && yColumn->isValid(row)
+				&& (!xColumn->isMasked(row)) && (!yColumn->isMasked(row)) ) {
+
+				if (xColMode == AbstractColumn::DateTime)
+					xValue = xColumn->dateTimeAt(row).toMSecsSinceEpoch();
+				else
+					xValue = xColumn->valueAt(row);
 
-	AbstractColumn::ColumnMode xColMode = xColumn->columnMode();
-	AbstractColumn::ColumnMode yColMode = yColumn->columnMode();
+				if (yColMode == AbstractColumn::DateTime)
+					yValue = yColumn->dateTimeAt(row).toMSecsSinceEpoch();
+				else
+					yValue = yColumn->valueAt(row);
 
-	//take over only valid and non masked points.
-	for (int row = 0; row < xColumn->rowCount(); row++) {
-		if ( xColumn->isValid(row) && yColumn->isValid(row)
-		        && (!xColumn->isMasked(row)) && (!yColumn->isMasked(row)) ) {
-			switch (xColMode) {
-			case AbstractColumn::Numeric:
-			case AbstractColumn::Integer:
-				tempPoint.setX(xColumn->valueAt(row));
-				break;
-			case AbstractColumn::Text:
-				break;
-			case AbstractColumn::DateTime:
-				tempPoint.setX(xColumn->dateTimeAt(row).toMSecsSinceEpoch());
-				break;
-			case AbstractColumn::Month:
-			case AbstractColumn::Day:
-				break;
-			}
+				if (abs(symbolPointsLogical.last().x() - xValue) < dxMinLogical && abs(symbolPointsLogical.last().y()-yValue)< dyMinLogical)
+					continue;
 
-			switch (yColMode) {
-			case AbstractColumn::Numeric:
-			case AbstractColumn::Integer:
-				tempPoint.setY(yColumn->valueAt(row));
-				break;
-			case AbstractColumn::Text:
-				break;
-			case AbstractColumn::DateTime:
-				tempPoint.setY(yColumn->dateTimeAt(row).toMSecsSinceEpoch());
-				break;
-			case AbstractColumn::Month:
-			case AbstractColumn::Day:
-				break;
+				symbolPointsLogical.append(QPointF(xValue, yValue));
+				connectedPointsLogical.push_back(true);
+
+			} else {
+				if (!connectedPointsLogical.empty())
+					connectedPointsLogical[connectedPointsLogical.size()-1] = false;
 			}
-			symbolPointsLogical.append(tempPoint);
-			connectedPointsLogical.push_back(true);
-		} else {
-			if (!connectedPointsLogical.empty())
-				connectedPointsLogical[connectedPointsLogical.size()-1] = false;
 		}
+
+	}
 	}
 
 	//calculate the scene coordinates