Just a quick thought:
    Wouldn't there be a lot less overhead if you just created a module; then declared your global variables as such:

         module1()

              public num as Int16

         end Module

You can then reference them from any WinForm in the project without dimensioning or re-instanciating them at all.
for example....

Private Sub btn1_Click(byVal Sender as Object, e as EventArgs) Handles btn1.Click
            
        Dim a as int16 = 100
        Dim b as int16 = 10

        num = a*b

        messageBox.show("The new number is " & num)

End Sub