@daflores63 It is odd that sending a test email was immediate but processing the queue has a 10s delay for each email for both SMTP and using the API.
If you continue to use the API wilth the SendGrid plugin then you can enable curl logging by modifying this line in file SendGridPlugin.php. It should be line 105
$this->mailSender = new MailSender($client, false, 1, false, false, true);
to
$this->mailSender = new MailSender($client, false, 1, false, true, true);
Then the plugin will enable curl verbose output and write that to a file curl.log in the directory identified by the $tmpdir variable in config.php. Not sure exactly what information that shows but might show timings.