Help! Site Crashing On Data Access When Busy!

Clearly, my code isn't written as well as it should be.  I don't understand enough about data access and could use some help.
I have several database tables, but one primary table that is the most accessed.  Generally, I need to build a list from the data based on some filter.  I'm using a repeater control, since all I need to display per record is a name, maybe a city or birthday, and possibly a little graphic, and my customer doesn't want a grid type of display.   The filter is determined by the page requested.   The exception is a search page where the user builds the filter and a grid is used to display the results.
The results always contain a link to a page that has more detail on the selected record. 
What is the best way to handle this?  I'm still trying to get a handle on different ways to get data and I'm not doing much with caching.  Would it make sense to keep the data in memory from the page that displays the list (or search page) to the detail page?  What if the detail page is accessed directly, say from a bookmark?  How do I cache this?
I'm currently using strongly typed datasets.
Below is an example of what I'm doing - this is from the code behind of one of the list pages - members with birthdays this month.
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim theMonth As String = DateTime.Now.ToString("MMMM")
        Me.LabelMonth.Text = theMonth

        Dim MemberAdapter As New WAPTableAdapters.membersTableAdapter
        Repeater1.DataSource = MemberAdapter.GetBirthday("Female", DatePart("m", Today))
        Repeater1.DataBind()
        Repeater2.DataSource = MemberAdapter.GetBirthday("Male", DatePart("m", Today))
        Repeater2.DataBind()
    End Sub

    Protected Sub Repeater1_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.RepeaterItemEventArgs) Handles Repeater1.ItemDataBound
        If e.Item.ItemType = ListItemType.Item OrElse e.Item.ItemType = ListItemType.AlternatingItem Then
            Dim LabelIcon As Label = CType(e.Item.FindControl("LabelIcon"), Label)
            Dim person As WAP.membersRow = CType(CType(e.Item.DataItem, System.Data.DataRowView).Row, WAP.membersRow)
            If System.IO.File.Exists(Server.MapPath("~/images/picts/" & person.FILE2 & ".jpg")) Then
                LabelIcon.Visible = True
            End If
        End If
    End Sub

    Protected Sub Repeater2_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.RepeaterItemEventArgs) Handles Repeater2.ItemDataBound
        If e.Item.ItemType = ListItemType.Item OrElse e.Item.ItemType = ListItemType.AlternatingItem Then
            Dim LabelIcon As Label = CType(e.Item.FindControl("LabelIcon"), Label)
            Dim person As WAP.membersRow = CType(CType(e.Item.DataItem, System.Data.DataRowView).Row, WAP.membersRow)
            If System.IO.File.Exists(Server.MapPath("~/images/picts/" & person.FILE2 & ".jpg")) Then
                LabelIcon.Visible = True
            End If
        End If
    End Sub

It seems pretty simple and straightforward to me, but these pages shouldn't be crashing when the site gets busy, so I have to be doing something wrong. 
Diane