vb.net - Trying To Create A Small Mail App - Getting Lag When Checking For Mail And Typing New Message -

in application working on, have built functionality allows users send 'mini' emails each other. basically, output contents mysql db, , poll db check if there entries db user read=false status. have form shows inbox (and outbox) of messages refreshes when open. problem finding when user types detail message body field, there constant lag every xx when software checks db new messages.

i know haven't set correctly , i'm therefore after best method of building routine.

mainform: has timer fires every 5 seconds runs query against db , returns integer value select count(*) mail is_read = 0 , recipient = " & current_user.id

showmessagesform: when opened, makes initial query db , returns messages current user datatable. clears listview control , re-populates using datatable.

private sub loadmessages()     dim querystring string      try         'populate inbox         lsvmail.items.clear()         if inboxdatatable isnot nothing inboxdatatable.clear()         querystring = "select m.id, recipient.display_name recipient, sender.display_name sender, m.subject, m.body, m.call_id, m.is_read, m.replied, m.followup, m.deleted, m.sent_deleted, m.sent " & _                         "from mail m " & _                         "left join clients sender on m.sender = sender.id " & _                         "left join clients recipient on m.recipient = recipient.id " & _                         "where m.recipient = " & current_user.id & " , m.deleted = 0 " & _                         "order m.sent desc"         inboxdatatable = db_connection.returndata(querystring)         if inboxdatatable.rows.count > 0             x = 0 (inboxdatatable.rows.count - 1)                 dim lvi new listviewitem(inboxdatatable.rows(x)("replied").tostring)                 lvi.subitems.add(inboxdatatable.rows(x)("sender").tostring)                  if cbool(inboxdatatable.rows(x)("is_read")) = true                     lvi.font = regularfont                 else                     lvi.font = boldfont                 end if                  if cbool(inboxdatatable.rows(x)("followup")) = true                     lvi.forecolor = color.red                 else                     lvi.forecolor = color.black                 end if                  lvi.subitems.add(decryptdata(inboxdatatable.rows(x)("subject").tostring))                 lvi.subitems.add(inboxdatatable.rows(x)("sent").tostring)                 lvi.subitems.add(inboxdatatable.rows(x)("followup").tostring)                 lvi.name = inboxdatatable.rows(x)("id").tostring                 lsvmail.items.add(lvi)             next         end if      catch ex exception         createlog("module: frmshowmessages: loadmailmessages()" & vbnewline & "exception error: " & ex.message)         msgbox("exception error: " & ex.message, msgboxstyle.critical, "module: frmshowmessages: loadmailmessages()")     end try end sub 

there timer control on form fires every 5 seconds runs above sub routine everytime.

composemessageform: contains subject textbox , body richtextbox control.

when enter text richtextbox, finding everytime timer triggers on showmessagesform, creates lag in typing on form.

so basically, guess asking best method of creating small application checks messages? needs check on main form see if user has new messages, , refresh inbox listview in case messages arrive whilst form open.

thanks in advance.

you must use multiple threads such case. way polling logic implemented in separate thread , not affect rest of application.