Index: sources/gui/qml/components/BaseChart.qml
===================================================================
diff -u -raf06f02c35f69afe8c8cf9e45873161075dab3ac -rf9133f0e1044c4ab68291eca66cd88f0a2c8a9b4
--- sources/gui/qml/components/BaseChart.qml	(.../BaseChart.qml)	(revision af06f02c35f69afe8c8cf9e45873161075dab3ac)
+++ sources/gui/qml/components/BaseChart.qml	(.../BaseChart.qml)	(revision f9133f0e1044c4ab68291eca66cd88f0a2c8a9b4)
@@ -89,14 +89,27 @@
         _xAxis.min = new Date(_xAxis.min.getTime() + hourMs)
         _xAxis.max = new Date(_xAxis.max.getTime() + hourMs)
 
-        // remove points left of the window
-        while (_line1.count > 0 && _line1.at(0).x < _xAxis.min.getTime()) {
-            _line1.remove(0)
-            _line2.remove(0)
-            _line3.remove(0)
-        }
+//        removeOldPoints()
+        _line1.removePoints(0, vMin)  // remove in batch
+        _line2.removePoints(0, vMin)  // remove in batch
+        _line3.removePoints(0, vMin)  // remove in batch
     }
 
+    // remove points old left of the window that are not shown
+    function removeOldPoints() {
+        var minX = _xAxis.min
+        var i = 0
+
+        // Find how many points to remove that are less thatn visible x axis min
+        while (i < _line1.count && _line1.at(i).x < minX)
+            i++
+
+        if (i > 0)
+            _line1.removePoints(0, i)  // remove in batch
+            _line2.removePoints(0, i)  // remove in batch
+            _line3.removePoints(0, i)  // remove in batch
+    }
+
     Timer { id: _timer
         interval    : _root.plotFrequency
         running     : false