Why does phpmailer take 15+ seconds to load? - php

Question

I recently setup phpmailer as my SMTP sending script to use for a website I've been working on and it's been nothing but a headache. My setup is IIS, and I'm currently using office365 to send out emails(although I have tried gmail and the results were no faster).I would appreciate any and all advice on how to speed this up, or if there's a way to post to a php file from javascript or php and then just let it work I could do that too. I'm trying to stay away from cron jobs if possible.
my script:
function sendMail($code, $email) {
//Create a new PHPMailer instance
$mail = new PHPMailer;
//Tell PHPMailer to use SMTP
$mail->isSMTP();
//Enable SMTP debugging
// 0 = off (for production use)
// 1 = client messages
// 2 = client and server messages
$mail->SMTPDebug = 0;
//Ask for HTML-friendly debug output
$mail->Debugoutput = 'html';
//Set the hostname of the mail server
$mail->Host = "smtp.office365.com";
//Set the SMTP port number - likely to be 25, 465 or 587
$mail->Port = 587;
//Whether to use SMTP authentication
$mail->SMTPAuth = true;
//Username to use for SMTP authentication
$mail->Username = "support#[domain redacted].com";
//Password to use for SMTP authentication
$mail->Password = "[password redacted]";
//enable TLS
$mail->SMTPSecure = 'tls';
//Set who the message is to be sent from
$mail->setFrom('support#[domain redacted].com', '[redacted]');
//Set an alternative reply-to address
$mail->addReplyTo('support#[domain redacted].com', '[redacted]');
//Set who the message is to be sent to
$mail->addAddress($email);
//Set the subject line
$mail->Subject = 'This is a test email from EdTester Support';
//Read an HTML message body from an external file, convert referenced images to embedded,
//convert HTML into a basic plain-text alternative body
$mail->Body = "Hello there, This is your activation e-mail. Please go to: http://[domain redacted]/activate.php?code=". $code . "&email=" . $email;
//Replace the plain text body with one created manually
$mail->AltBody = 'This is a plain-text message body';
//send the message, check for errors
if (!$mail->send()) {
echo "Mailer Error: " . $mail->ErrorInfo;
} else {
echo "Message sent!";
}
}