New Post: Problems PHPExcel - Excessive Overhead of memory

$periodo = $objRel->getPeriodo();
        foreach($periodo as $kp =>$p){
            if(is_numeric($kp)){
                $pX = strtoupper(gmstrftime("%h", strtotime($p)));
                $pP = substr($p, 0,7);
                $objWorkSheet = $objPHPExcel->createSheet($kp); 
                $objWorkSheet->setTitle($pX);
                $objWorkSheet->mergeCells('A3:B3');
                $objWorkSheet->freezePane('C4');
                $objWorkSheet->setCellValue("A3","Classif");

                $i = 4;
                foreach($arrMatrixClass as $k => $v){
                    $output = mb_convert_encoding($v,"UTF-8", "ISO-8859-1");
                    $objWorkSheet->setCellValue("A".$i,$k)
                                 ->setCellValue("B".$i,$output);
                    if(substr($k,2) != "00"){
        //                $this->SyncClassToObra($Sheet,$i,$Sheet->getTitle(),$k,"C");
                        $l = 'C';
                        //$p = $objWorkSheet->getTitle();
                        $arrObras = $objRel->getObras();
                        $this->tst[] = $arrObras;
                        foreach ($arrObras as $ObjObra){
                            $objWorkSheet->setCellValue($l."3",$ObjObra->getObraNum());
                            $arrCC = $ObjObra->getClassCusto();
                            if(isset($arrCC[$pP])){
                                $objWorkSheet->setCellValue($l.$i,$arrCC[$pP][$k]);
                            }
                            $l++;
                        }
                        //echo 'secs. Memory usage: ', round(((memory_get_usage(true) / 1024) / 1024), 2), 'Mb</br>';
                    }
                    $i++;
                }
            }
        }