关于发送电子邮件通知的性能改进建议？

It takes around a couple of seconds for my app to execute the code to send an email right now on a test server with nothing much else running. Not sure if this is typical/expected. I'm also using the php framework Kohana's email helper and not php's mail directly out of convenience if that matters. Is it always just better to schedule a cron job to send emails every 5 min or so? Or should I be able to send emails immediately and I'm just not doing something right? It takes around a couple of seconds for my app