Disabling View State of controls you dont need explicitly, for example there are many controls on your page, which may not require viewstate, like menus, some hyperlinks, some display statistics labels etc, turn off them a bit.
Also another thing you can do is, reduce the control ID length, this will improve the page size to a much better level.
Your control IDs are like following
PageContainer1_MyLoginContainerUserControl1_MyLoginForm1_MyUsername1
PageContainer1_MyCustomerDataGrid1_item0_MyCustomerNameLabel
I know it sounds little bad, but if you notice the grid/list items put so many big control IDs like this, we noticed that by reducing certain characters in ID also helps improving page size. In list/gridview etc it improves this by 30% to 40%, also nested user controls are bad as well, when you really dont think you need control's ID anymore, just put it 3 letter big max.