High CPU consumption by a PHP script - php

Question

My hosting service provider has disabled my account 2 times due to one of my image resizing PHP scripts. The script is lead-img, which is pasted here:
include ("videothumb.php");
function amty_lead_img($w='',$h='',$constrain='',$img='',$percent='',$zc='',$post_id = '',
$img_url_only = 'y',$show_default = 'y',$default_img = '') {
if($img == ''){
if($post_id == ''){
global $id;
$img = amty_take_first_img_by_id($id);
}
else
$img = amty_take_first_img_by_id($post_id);
}
if($img =='' && $show_default != 'y'){
$img_url = $img;
}else{
if($img =='' && $show_default == 'y'){
if($default_img != '')
$img = $default_img;
else
$img = WP_PLUGIN_URL . "/amtythumb/amtytextthumb.gif";
}
if($constrain != '')
$constrain='constrain='. $constrain . '&';
if($h != '')
$h='h='. $h . '&';
if($w != '')
$w='w='. $w . '&';
if($zc != '')
$zc='zc='. $zc . '&';
if($percent != '')
$percent='percent='. $percent . '&';
$img_url = WP_PLUGIN_URL . "/amtythumb/scripts/imgsize.php?".$zc."". $percent."".$constrain."" . $w ."" . $h ."&img=" . $img ;
}
if($img_url_only == "y"){
$out = $img_url;
}else{
$out = '<img src="'.$img_url.'" />';
}
//echo $out;
return $out;
}//function end
function amty_take_first_img_by_id($id) {
$temp = $wp_query; // assign orginal query to temp variable for later use
$wp_query = null;
global $wpdb;
$img='';
$attach_img='';
$uploaded_img = '';
$image_data = $wpdb->get_results("SELECT guid, post_content, post_mime_type, post_title FROM wp_posts WHERE id = $id");
$match_count = preg_match_all("/<img[^']*?src=\"([^']*?)\"[^']*?\/?>/", $image_data[0]->post_content, $match_array, PREG_PATTERN_ORDER);
if($match_count == 0){
/*$match_count = preg_match_all("/<img[^']*?src=\"([^']*?)\"[^']*?>/", $image_data[1]->post_content, $match_array, PREG_PATTERN_ORDER);
if($match_count == 0){
$match_count = preg_match_all("/<img[^>]+>/i", $image_data[1]->post_content, $match_array, PREG_PATTERN_ORDER);
if($match_count == 0)
$match_count = preg_match_all("/<img[^']*?src=\"([^']*?)\"[^']*?\/>/", $image_data[0]->post_content, $match_array, PREG_PATTERN_ORDER);
if($match_count == 0){*/
$img = thumb($image_data[0]->post_content);
/*}
}*/
}
if( $img == '') $img = $match_array[1][0];
$attach_img = amty_get_firstimage($output->guid);
$first_image_data = array ($image_data[0]);
foreach($first_image_data as $output) {
if (substr($output->post_mime_type, 0, 5) == 'image'){
$uploaded_img = $output->guid;
break;
}
}
$wp_query = $temp;
if( $img != '') return $img;
if( $attach_img != '') return $attach_img;
if( $uploaded_img != '') return $uploaded_img;
return '';
}
//get First attached image
function amty_get_firstimage($post_id='', $size='thumbnail') {
$id = (int) $post_id;
$args = array(
'post_type' => 'attachment',
'post_mime_type' => 'image',
'numberposts' => 1,
'order' => 'ASC',
'orderby' => 'menu_order ID',
'post_status' => null,
'post_parent' => $id
);
$attachments = get_posts($args);
if ($attachments) {
$img = wp_get_attachment_image_src($attachments[0]->ID, $size);
return $img[0];
}else{
return '';
}
}
?>
This script is calling another script "videothumb.php" for accessing image for a video url from respective site and to resizing it.
I am not able to figure out anything wrong with the script. I checked the log to ensure how many times it was called etc. But everything seems normal.
Can someone guide me which part of script can slow down the CPU or can increase server load?