Call a modal using function

I have a table, which lists driver data, which when clicking on a table column triggers a modal.

But I want, when clicking, to call a function, which returns the modal, and not every time you load the page, already load the modal. Follow the snippet of code. This way, it works perfectly, but it's getting very slow, so I want to know if you have a%

<?php


if($PERMOT != 0)
{
        echo "<td><a data-toggle='modal' data-target='#modal-$i'>".number_format($log[0], 3)."</a>             </td>";//Gasto
        echo "<td class=".$classTd."><a data-toggle='modal' data-arget='#modal-$i'>".number_format($log[5], 3)."</a></td>";//Diff
                        }
                        else
                            echo "<td><div>-</div><div>-</div><div>-</div></td>";

                    echo "</tr>";
                echo "</tbody>";
                echo "
                    <div class='modal fade' id='modal-$i'>
                        <div class='modal-dialog modal-lg'>
                            <div class='modal-content'>
                                 <div class='modal-header'>
                                    <h4 class='modal-title'>Documento ".$CODFIL."-".$SERDOC." - ".$NUMDOC." </h4>
                                  </div>
                                  <div class='modal-body'>
                                     ".$log[6]."
                                  </div>
                                  <div class='modal-footer'>
                                      <button type='button' class='btn btn-danger' data-dismiss='modal'>Fechar</button>
                                   </div>                   
                            </div>
                        </div>
                    </div>
                ";

                //echo "<button class='info plus  ' id='".$i."' onclick='moreInf($i, $CODFIL, $SERDOC, $NUMDOC)'></button>";
                $i++;

?>