Speeding up a very slow PHP script generating a large JSON array - php

Question

I currently have a web-app running on AppEngine that uses PHP to initially generate a giant JSON array, which Javascript then uses to populate elements of my web-app.
The following code works perfectly and does everything I want, however takes about 10 seconds to execute. Might not sound like a lot, but it certainly feels out of place. I'm wondering what I should be doing differently to speed up the creation of the initial array.
I've so far thought about attacking this a few ways;
I could load less data initially, reducing load times as there is
literally less to load. This would effect the general performance
though, as right now once the data is loaded, each "section" is
instant to be populated and super fast.
I could cache some data using App Engine's
built in Memcache. This is a neat idea however the data generated
changes often. Often enough that a cache just wont do it.
Use Web
Sockets instead. I want to eventually do this, and it's on the to-do
list, however this would mean rewriting a lot of code, so I'm not too
fond of this right now.
I'm sure there are some "bad practise" bits and pieces within my code as well, feel free to point them out and scold me for it... Here's the same code below as a Gist if you prefer it that way.
<?php
use google\appengine\api\cloud_storage\CloudStorageTools;
# ===================================== #
# ==== Generate App Settings Array ==== #
# ===================================== #
//Existing Class (not shown) already generated $app for us...
$app_settings_array = array('app_version' => $app->app_version, 'app_server' => $_SERVER['SERVER_SOFTWARE'], 'app_id' => $app->app_id, 'app_name' => $app->app_name, 'app_logo_dark' => $app->app_logo_dark, 'app_logo_light' => $app->app_logo_light, 'app_motd' => $app->app_motd, 'app_domain' => $app->app_domain);
# ===================================== #
# ==== Generate User Details Array ==== #
# ===================================== #
$currentuser = $_SESSION['user_id']; //Get current user id from session
$user_info = $db->prepare("SELECT * FROM hr_personal WHERE employee_id = :user_id LIMIT 1");
$user_info->bindParam(':user_id', $currentuser);
$user_info->execute();
$user = $user_info->fetch(PDO::FETCH_OBJ);
$email_hash = hash_hmac('sha256', $user->employee_id, '_redactedkey');
$log_info = $db->prepare("SELECT log_time FROM app_log WHERE log_user = :user_id ORDER BY log_time ASC LIMIT 1"); //Get
$log_info->bindParam(':user_id', $currentuser);
$log_info->execute();
$first_seen = $log_info->fetch(PDO::FETCH_OBJ);
$user_details_array = array('id' => $user->employee_id, 'id_hash' => $email_hash, 'first_seen' => $first_seen->log_time, 'title' => $user->employee_title, 'name' => $user->employee_knownas, 'avatar' => $user->employee_avatar, 'mobile' => $user->employee_mobile, 'email' => $user->employee_email);
# ============================= #
# ==== Generate Chat Array ==== #
# ============================= #
$currentuser = $_SESSION['user_id'];
$currentapp = $app->app_id;
$chat_array = array();
foreach (range('A', 'Z') as $char) {
$individuals = array();
$countrow = $db->prepare("SELECT * FROM hr_personal where employee_knownas LIKE '$char%' AND employee_id IN (SELECT notification_submitter FROM notification_sent WHERE notification_id IN (SELECT notification_id FROM notification_wait WHERE user_id = '$currentuser' AND method = 'online' ORDER BY notification_id DESC))");
$countrow->execute();
if ($countrow->rowCount() > 0) {
$mesage_query = "SELECT * FROM hr_personal where employee_knownas LIKE '$char%' AND employee_id IN (SELECT notification_submitter FROM notification_sent WHERE notification_id IN (SELECT notification_id FROM notification_wait WHERE user_id = '$currentuser' AND method = 'online' ORDER BY notification_id DESC))";
$message_query_run = $db->query($mesage_query);
while($row = $message_query_run->fetch(PDO::FETCH_ASSOC)) {
if(!empty($row['employee_avatar'])){
$options = ['size' => 200, 'crop' => true];
$image_file = "gs://rouic-cdn/internal/".$row['employee_avatar'];
$image_url = CloudStorageTools::getImageServingUrl($image_file, $options);
$image_url = preg_replace("/^http:/i", "https:", $image_url);
} else {
$image_url = "";
}
$whileUser = $row['employee_id'];
$message_chain = array();
$chain_query = "SELECT * FROM notification_wait WHERE method = 'online' AND user_id = '$currentuser' AND notification_id IN (SELECT notification_id FROM notification_sent WHERE notification_submitter = '$whileUser')";
$chain_query_run = $db->query($chain_query);
while($chainRow = $chain_query_run->fetch(PDO::FETCH_ASSOC)) {
array_push($message_chain, array('id' => $chainRow['notification_id'], 'reply_id' => $chainRow['reply_id'], 'content' => $chainRow['message'], 'time' => $chainRow['time'], 'state' => $chainRow['state']));
}
array_push($individuals, array('id' => $row['employee_id'], 'group' => $char, 'name' => $row['employee_knownas'], 'avatar' => $image_url, 'message_chain' => $message_chain));
}
array_push($chat_array, array('group' => $char, 'data' => $individuals));
}
}
# ========================================== #
# ==== Generate Admin Groups (if admin) ==== #
# ========================================== #
$admin_array = array();
if($auth->checkPage('admin', $_SESSION['user_id']) == false){ //Existing CheckPage class returns true if user is allowed on page
array_push($admin_array, array('access' => 'denied'));
} else {
//Generate All Clients
$client_array = array();
$client_query = "SELECT * FROM clients WHERE client_app = '$currentapp'";
$client_query_run = $db->query($client_query);
while($row = $client_query_run->fetch(PDO::FETCH_ASSOC)) {
if(!empty($row['client_avatar'])){
$options = ['size' => 200, 'crop' => true];
$image_file = "gs://rouic-cdn/internal/".$row['client_avatar'];
$image_url = CloudStorageTools::getImageServingUrl($image_file, $options);
$image_url = '<span class="thumbnail-wrapper d48 circular inline m-t-5">
<img id="dynamicavy" src="'.preg_replace("/^http:/i", "https:", $image_url).'" width="48" height="48">
</span>';
} else {
$image_url = "";
}
$short_desc = strlen($row['client_desc']) > 30 ? substr($row['client_desc'],0,30)."..." : $row['client_desc'];
$desc = '<span class="expandable" full-length="'.$row['client_desc'].'">'.$short_desc.'</span>';
$actions = '<button class="btn btn-xs btn-primary">Edit Details</button>';
array_push($client_array, array($row['client_id'], $image_url, "<b>".ucwords($row['client_name'])."</b>", $row['client_dob'], $row['client_phone'], $row['client_address'], $desc, $actions));
}
//Generate All Departments
$department_array = array();
$department_query = "SELECT * FROM departments WHERE dep_app = '$currentapp'";
$department_query_run = $db->query($department_query);
while($row = $department_query_run->fetch(PDO::FETCH_ASSOC)) {
if(!empty($row['dep_avatar'])){
$options = ['size' => 200, 'crop' => true];
$image_file = "gs://rouic-cdn/internal/".$row['dep_avatar'];
$image_url = CloudStorageTools::getImageServingUrl($image_file, $options);
$image_url = '<span class="thumbnail-wrapper d48 circular inline m-t-5">
<img id="dynamicavy" src="'.preg_replace("/^http:/i", "https:", $image_url).'" width="48" height="48">
</span>';
} else {
$image_url = "";
}
$short_desc = strlen($row['dep_description']) > 30 ? substr($row['dep_description'],0,30)."..." : $row['dep_description'];
$desc = '<span class="expandable" full-length="'.$row['dep_description'].'">'.$short_desc.'</span>';
$actions = '<button class="btn btn-xs btn-primary">Edit Details</button>';
array_push($department_array, array($row['dep_id'], $image_url, "<b>".ucwords($row['dep_name'])."</b>", $desc, $actions));
}
array_push($admin_array, array('access' => 'granted', 'allDepartments' => $department_array, 'allClients' => $client_array));
}
... About 4 More sections redacted ...
# ===================== #
# ==== Final Array ==== #
# ===================== #
$init_array_compare = array('chat' => $chat_array, 'admin' => $admin_array, 'app_details' => $app_settings_array, 'user_details' => $user_details_array, 'user_permissions' => $user_permissions_array);
$hash = md5(json_encode($init_array_compare)); //I'm basically creating a hash of the results here so I can see if anything has changed if generated again
$init_array = array('hash' => $hash, 'chat' => $chat_array, 'admin' => $admin_array, 'app_details' => $app_settings_array, 'user_details' => $user_details_array, 'user_permissions' => $user_permissions_array);
echo json_encode($init_array);

Answer 1

MonkeyZeus was completely correct, it turned out to be CloudStorageTools::getImageServingUrl() causing the hanging. After writing a script to cache the URL's it generated the script now runs in under a second.