Send the WM_PAINT message. It's 3-4 times faster.

Code:
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Const WM_PAINT = &HF

Private Sub Command1_Click()
    SendMessage Picture1.hwnd, WM_PAINT, Picture1.hDC, 0
End Sub