[AccessD] problem of a listbox's response on network...

hi to all,
I am working on a mdb file (office 2010) under linked tables from another 
database which is installed on a home network (workgroup 192.168.0.xx)
For quick searching on basics fields (name, year born etc) every user on the 
network is working with a deigned form including an unbound list box

on a text unbound
Private Sub text_box_Change()
Me![list2].RowSource = "SELECT [AM], [Last_name], [First_name], 
[Father_name], [year_born] FROM [q_start_list] WHERE [Last_first_name]like 
'" & Me![text_box].Text & "*'"
End Sub

on a button
Private Sub list2_DblClick(Cancel As Integer)
    Dim stDocName As String
    Dim stLinkCriteria As String
    stDocName = "MT_basic_char"
    stLinkCriteria = "[AM] = " & Me!list2.Value & ""
    DoCmd.OpenForm stDocName, , , stLinkCriteria
End Sub

what it happens... if only one person is connected working on the listbox 
there is no problem at all while the response returns on the spot
But when more than one try to work on the same listbox the response is 
ridiculously slow...

Is there any idea about which is the reason it happens?

thank’s in advance
/kostas