Memory usage still high for Powerpoint even after VBA Macro is executed

I have created some VBA tools in Powerpoint to help save time while working on data charts. One of the tools sorts the data in the chart on each selected slide from highest to lowest.

When I run this code on multiple slides at once, the memory usage for vba goes up significantly (2x to 3x or more depending on the number of charts). However, once the macro is finished running, the memory allocation for Powerpoint never goes back down until I quit the program, often making the computer completely unusable.

Any help on how I can prevent this would be greatly appreciated!

Here is the code in question:

Sub Sortchart()
Dim shp As PowerPoint.Shape
Dim sld As Slide
Dim mychart As PowerPoint.Chart
Dim lastRow As Long
Dim LastCol As Long

For Each sld In ActiveWindow.Selection.SlideRange
    For Each shp In sld.Shapes
        If shp.HasChart Then
            Set mychart = shp.Chart
            With mychart
                Set mysheet = .ChartData.Workbook.Sheets(1)
                With mysheet
                    lastRow = mysheet.usedrange.Rows.Count
                    LastCol = mysheet.usedrange.Columns.Count + 1
                    If LastCol > 3 Then
                        MsgBox "This chart is not sortable. Please do it manually."
                    Else
                        .Range(.Cells(1, LastCol - 1), .Cells(lastRow, LastCol)).sort Key1:=.Range("C1"), Order1:=1, Header:=xlyes
                    End If
                End With
            End With
        End If
    Next shp
Next sld
Set shp = Nothing
Set sld = Nothing
Set mychart = Nothing
End Sub

I encountered a similar problem recently, and it seems that after accessing the
myShape.Chart.ChartData.Workbook property in PowerPoint, the Workbook is loaded and kept in memory by default.

To prevent unnecessary memory usage, the Workbook can be closed and unloaded from memory by calling
myShape.Chart.ChartData.Workbook.Application.Quit when the specific Workbook is not accessed anymore in the code.