How can Microsoft Outlook be slower then your mobile email?

Everyday, my mobile phone seems to receive an email quicker than my desktop email client. The only reason for it that I can identify is that Microsoft Outlook must be checking the Exchange server periodically for updates while the Exchange server is pushing emails it receives out to the mobile device immediately.

Is that true?

If so wouldn’t it be more efficient to implement push technology on the desktop Outlook clients? This would save server resources and network traffic.. right?