For a start you could speed it up, even a small way, by the more efficient:

With thisform.pageframe1.page3
  .grid1.DeleteMark= .F.
  .RecordMark= .F.
  .RowHeight=30
  .column1.Width=100
  .column2.Width=375
  .column3.Width=75
EndWith

>below code in init event of the form
>
>

>thisform.pageframe1.page3.grid1.DeleteMark= .F.
>thisform.pageframe1.page3.grid1.RecordMark= .F.
>thisform.pageframe1.page3.grid1.RowHeight=30
>thisform.pageframe1.page3.grid1.column1.Width=100
>thisform.pageframe1.page3.grid1.column2.Width=375
>thisform.pageframe1.page3.grid1.column3.Width=75
>

>
>below code in grid1.column1.text1.valid
>
>

>Select PARTYCD
>PARTYCDREC=Recno()
>varea=.T.
>luretval=Alltrim(This.Text)
>If (!Seek(PARTYCD.compcode,'tcust','accode') And !Empty(PARTYCD.compcode)) Or Lastkey()=-1
>   aabb=Alltrim(This.Text)
>   Do comphelp With PARTYCD.compcode
>   Wait Window Timeout .01
>   If Not Empty(luretval)
>      Sele PARTYCD
>      If Seek(luretval,"tcust","accode")
>         Select PARTYCD
>         Goto PARTYCDREC
>         Replace PARTYCD.compcode With tcust.accode, PARTYCD.compname With tcust.acname
>      Endif
>   Endif
>Endif
>Select PARTYCD
>Goto PARTYCDREC
>If Empty(PARTYCD.compcode)
>   Return
>Endif
>
>If Seek(PARTYCD.compcode,'tcust','accode')
>   Replace PARTYCD.compname With tcust.acname
>Else
>   varea=.F.
>Endif
>Select PARTYCD
>Goto PARTYCDREC
>Return varea
>

>
>
>below code in when event of grid1.column2.text.when
>
>

>RETURN .F.
>

>
>below code in valid event of grid1.column3.text.valid
>
>

>SELECT partycd
>IF cdrt#0
>   APPEND BLANK
>   REPLACE accode WITH customer.accode
>   KEYBOARD '{DNARROW}'
>ENDIF
>

>
>warm regards,
>mk.