phpexcel 导出数据耗时，求教

导出7000条数据耗时20秒。求教，我那里弄的不对了。function  exportExcel($data_array,$array,$filename){

$letters_arr=array( '1'=>'A','2'=>'B','3'=>'C','4'=>'D','5'=>'E',
'6'=>'F','7'=>'G','8'=>'H','9'=>'I','10'=>'J',
'11'=>'K','12'=>'L','13'=>'M','14'=>'N','15'=>'O',
'16'=>'P','17'=>'Q','18'=>'R','19'=>'S','20'=>'T',
'21'=>'U','22'=>'V','23'=>'W','24'=>'X','25'=>'Y',
'26'=>'Z','27'=>'AA','28'=>'AB','29'=>'AC','30'=>'AD',
'31'=>'AE','32'=>'AF','33'=>'AG','34'=>'AH','35'=>'AI',
'36'=>'AJ','37'=>'AK','38'=>'AL','39'=>'AM','40'=>'AN',
'41'=>'AO','42'=>'AP','43'=>'AQ','44'=>'AR','45'=>'AS',
'46'=>'AT','47'=>'AU','47'=>'AV','49'=>'AW','50'=>'AX',
'51'=>'AY','52'=>'AZ', );
foreach($data_array as $data){
$a=array();
foreach($array as $k=>$v){

$a[]=$data[$k];
}
$dataArray[]=$a;
}
Vendor('Zend.Classes.PHPExcel');

$objPHPExcel = new PHPExcel(); $count=count($array);
$count_2=count($dataArray);
$count_2=$count_2+3;
//首行设置
$objPHPExcel->setActiveSheetIndex(0)
   ->setCellValue('A1',$filename);
$objPHPExcel->getActiveSheet()->getStyle('A1')->getFont()->setSize(15);
$objPHPExcel->getActiveSheet()->getStyle('A1')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->mergeCells('A1:'.$letters_arr[$count].'1');
$objPHPExcel->getActiveSheet()->getStyle('A1:'.$letters_arr[$count].'1')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment::HORIZONTAL_CENTER);
//载入数据
$objPHPExcel->getActiveSheet()->fromArray($array, NULL, 'A3');
$objPHPExcel->getActiveSheet()->fromArray($dataArray, NULL, 'A4');
//设置边框
$sharedStyle1 = new PHPExcel_Style();
$sharedStyle1->applyFromArray(
array('borders'=>array(
'left'=> array('style' => PHPExcel_Style_Border::BORDER_THIN),
'right'=>array('style' => PHPExcel_Style_Border::BORDER_THIN),
'top'=>array('style' => PHPExcel_Style_Border::BORDER_THIN),
'bottom'=>array('style' => PHPExcel_Style_Border::BORDER_THIN)
)
)
);
$objPHPExcel->getActiveSheet()->setSharedStyle($sharedStyle1,'A3:'.$letters_arr[$count].$count_2);
 //设置表头填充颜色 
$objStyleA3 = $objPHPExcel->getActiveSheet()->getStyle('A3:'.$letters_arr[$count].'3');
$objStyleA3 = $objStyleA3->getFill();  
$objStyleA3->setFillType(PHPExcel_Style_Fill::FILL_SOLID);
$objStyleA3->getStartColor()->setARGB('FFFFBB'); header('Content-Type: application/vnd.ms-excel');
header('Content-Disposition: attachment;filename="'.$filename.'"');
header('Cache-Control: max-age=0');
$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel,'Excel5');
$objWriter->save('php://output');
exit;excelphpexcel