Hàm upload hình ảnh ntn để đỡ tốn BW và CPU usage?

	function imgupload($file, $name)
	{
		$image = $file['name'];
		$uploadedfile = $file['tmp_name'];
		if (!getimagesize($uploadedfile)) {
			echo 'Loi upload hinh anh!';
			return false;
		}

		if ($image) 
		{
			$filename = stripslashes($file['name']);
			$extension = $this->getExtension($filename);
			$extension = strtolower($extension);
			if (($extension != 'jpg') && ($extension != 'jpeg')
			&& ($extension != 'png') && ($extension != 'gif')) 
			{
				echo 'Ko dung dinh dang';
				return false;
			}
			else
			{
				$fsize = $file['size'];

				if($extension=='jpg' || $extension=='jpeg' )
				{
					$uploadedfile = $file['tmp_name'];
					$src = imagecreatefromjpeg($uploadedfile);
				}
				else if($extension=='png')
					{
						$uploadedfile = $file['tmp_name'];
						$src = imagecreatefrompng($uploadedfile);
					}
					else $src = imagecreatefromgif($uploadedfile);

				$infos = getimagesize($uploadedfile);
				$max = 800;
				$maxthumb = 160;
				$quatily = 80;
				
				$new = $this->resize($infos, $max, $max);
				$tmp = imagecreatetruecolor($new->w,$new->h);

				$newthumb = $this->resize($infos, $maxthumb, $maxthumb);
				$tmpthumb = imagecreatetruecolor($newthumb->w,$newthumb->h);

				imagecopyresampled($tmp,$src,0,0,0,0,$new->w,$new->h,
				$infos[0],$infos[1]);

				imagecopyresampled($tmpthumb,$src,0,0,0,0,$newthumb->w,$newthumb->h, 
				$infos[0],$infos[1]);

				$photoPath = $this->photoPath;
				$thumbsPath = $this->thumbsPath;
				
				$this->createfolder($photoPath);
				$this->createfolder($thumbsPath);
				
				$photoPath = $this->photoPath.DS.$name;
				$thumbsPath = $this->thumbsPath.DS.$name;

				imagejpeg($tmp,$photoPath,$quatily);
				imagejpeg($tmpthumb,$thumbsPath,$quatily);

				imagedestroy($src);
				imagedestroy($tmp);
				imagedestroy($tmpthumb);
			}
		}
		return true;
	}
	function resize($infos, $width, $height)
	{
		//Don't resize images which are smaller than thumbs
		if ($infos[0] < $width && $infos[1] < $height) {
			$iNew->w = $infos[0];
			$iNew->h = $infos[1];
			return $iNew;
		}
		// keep proportions
		$iWidth = $infos[0];
		$iHeight = $infos[1];
		$iRatioW = $width / $iWidth;
		$iRatioH = $height / $iHeight;

		if ($iRatioW < $iRatioH) {
			$iNew->w = $iWidth * $iRatioW;
			$iNew->h = $iHeight * $iRatioW;
		} else {
			$iNew->w = $iWidth * $iRatioH;
			$iNew->h = $iHeight * $iRatioH;
		}
		return $iNew;
	}