WinForms.DataGridView VirtualMode Collapsing rows

I am working on a WinForms Application, that have a DataGridView, this Control emulates a TreeView, so the RowCount changes drastically. I am having a performance issue when collapsing rows...

Example:

// dataGrid.VirtualMode = true;

// dataGrid.RowCount = 100.000;

dataGrid.RowCount = 2; // Is too Slow!