ContentPresenter layout pass

问题

I am trying to profile wpf application (to speed up ListView displaying complex multi-column datatemplated items). And I have problem to understand figures in application timeline report:

Description says:

Here is this column template (xaml):

<GridViewColumn Header="Header">
    <GridViewColumn.CellTemplate>
        <DataTemplate>
            <StackPanel>
                <StackPanel Orientation="Horizontal">

Questions:

• What means "Element" as a type of timeline item? Is it layout pass (as I understand it) or is it something else?
• Why sum of children ( only one child = 0.33 ms) is not equal total time (7.82 ms) ?
• What ContentPresenter was doing for 7.5 ms?

来源：https://stackoverflow.com/questions/38224212/contentpresenter-layout-pass