You can boot from a MicroSD card or an eMMC module. The MicroSD interface supports the higher performance UHS-1 mode as well.
File access of a 512MB file (read/write) on three different storage options shows distinct performance differences.
The eMMC 5.0 storage is ~7x faster than the MicroSD Class-10 card in read tests. The MicroSD UHS-1 card is ~2x faster than the MicroSD Class-10 card in read tests. The MicroSD UHS-1 card provides a great low-cost option for many applications!