Insert the SD Card in this way
Storage I/O comparison
To obtain the results in the storage I/O comparison graph, type the following lines at a command prompt. The first command tests the write speed, and the second command tests the read speed:
$ dd if=/dev/zero of=test.tmp oflag=direct bs=500K count=1024
$ dd if=test.tmp of=/dev/null iflag=direct bs=500K count=1024
If you use the eMMC storage, you can get about two to three times faster storage I/O read performance. However, an affordable microSD UHS-1 card can still achieve reasonably fast speeds thanks to the advanced SD 3.01 host controller in the S805 processor. The MicroSD card read performance on C1+ is still about 1.7 times faster then RPi if you use the UHS-1 memory card.