I´ve also got a SSD, i7 and always record the videos in FullHD 60fps.
Rendering a 15 Minutes Video takes about an hour. It makes no difference if I use my private notebook with a dedicated graphic card (Intel HD) or my working notebook with a Nvidia Quadro. As said, both use an i7 and the files were located on the ssd.
Which device creates the 15 Minutes files? The XE or you computer? The XE does it according to your SD card an its filesystem. At a specific filesize, a new fill will be created.
1 hour for 15 minutes? I will have about 3 hours of video 6 days a week I need to record and get on youtube. There is no way I could wait 12 hours per day for rendering!!!