Newbie PostBacks And State Of Controls?

In the Page_Load() event handler for one of my pages I use the new statement about 100 times equating to memory allocation for about 100 objects. As follows:

using System.Web.UI.WebControls;
Table mytable1 = new Table();
TableRow [] myrows = new TableRow[5];
TableCell [] mycells = new TableCell[100];
int i;
for(i=0; i<5; i++) myrows[i] = new TableRow();
for(i=0; i<100; i++) mycells[i] = new TableCell();

My question is, should all of these new statements be enclosed like so:

if(IsPostBack==false) {
// Initialize all controls for page just once during the session
}

Or should the Controls be freshly allocated, initialized, and added to the page each time the Page_Load event handler is called? I personally don't think its efficient to create mytable from scratch every Page_Load since all I really ever change is the contents of the table and not the table itself.