Performance issue with VXYModelMapper

Attached example reproduces big performance issue. If 

Reset all and updateAll is clicked.

Looks like  the function QXYModelMapperPrivate::modelUpdated there is a method
called oldPoint = m_series->points().at(index.row() - m_first) for each iteration.
This calling a function that is redundant and very slow because oldPoint is
not using and m_series->points() is converting vector to list.