How to speed up the running time of Google Apps Script?

Question

I am beginner in the world of programming, I created a script to go through table 1 and bring the values as they are in table 2 according to the periods informed in it.

The script works correctly but it is very slow at the time of execution. I would like a help to try to make it faster.

I researched about matrices but could not understand to apply in this function.

function teste() {

  var ss = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Página6");
  var tabela = ss.getRange(3, 9, ss.getLastRow(), 1).getValues();

  for(var l1 = 3 ; l1 <= tabela.length ; l1 ++ ){
    var tab1 = ss.getRange(l1,8).getValue();
    for( var l2 = 3 ; l2 <= tabela.length ; l2 ++ ){
      var tab2 = ss.getRange(l2,12).getValue();

      if (tab1 == tab2){

        for( var col = 13 ; col < 17 ; col ++){
             var coluna = ss.getRange(2, col).getValue();

          if( ss.getRange(l1, 9).getValue() == ss.getRange(2, col).getValue()){
               ss.getRange(l2, col).setValue(ss.getRange(l1, 10).getValue());
          }
        }
      }
    }
  } 
}