In reply to Mark Gavalda (@MarkGavalda).

It's not a different user or group, but I do have my test site setup to use PHP-FPM for my admin panel and HHVM for my front-end. I did this as I'm not sure how stable HHVM is just now, so I figured I may as well use the older slower PHP-FPM approach in the admin panel where performance isn't as mission critical.