比较最大日期速度求教！！！！

比较最大日期速度求教！！！！
我写了一个查找文件（二进制）中最大日期(里面有许多相同的日期）的程序，可是执行起来很慢（35k需要1分钟），请教个位打侠帮助修改一下，以提高速度，谢谢！！！！
以下是代码：
Private Type Record
DM(1 To 4) As Byte
MNAME(1 To 4) As Byte
date As Long
a1 As Long
a2 As Long
End Type
Private aa() As Record
Private mm() As Record
Private Sub Command1_Click()
Dim recordReal As Record
Dim recordTemp As Record
Dim dateReal As Date
Dim dateTemp As Date
Dim RecordLen As Long
Dim MaxRecords As Long

Open App.Path & "\1.dat" For Binary Access Read Write As #1
RecordLen = LenB(recordReal)
MaxRecords = (LOF(1) - 21) / RecordLen
ReDim aa(MaxRecords)
ReDim mm(MaxRecords)
For i = 0 To MaxRecords - 2
For j = 0 To MaxRecords - 2 - i
Get #1, 1 + j * RecordLen, aa(i)
dateTemp = Format(aa(i).date, "####-##-##")
Get #1, 1 + (j + 1) * RecordLen, mm(j) 'a[i+1]

dateReal = Format(mm(j).date, "####-##-##")

If dateTemp >= dateReal Then
Me.D1.Value = dateTemp
End If
Next
Next
Close #1
End Sub