Pi3 with SanDisk Ultra 16GB:
osmc@osmc::~$ time iozone -e -I -a -s 50M -r 4k -r 512k -i 0 -i 1 -i 2 | tail -4 | head -2 | awk '{print "Block Size " $2"k", "Write " $3/1024, "Rewrite " $4/1024, "Read " $5/1024, "Reread " $6/1024, "Random Read " $7/1024, "Random Write "$8/1024}'
Block Size 4k Write 6.02734 Rewrite 8.14453 Read 14.9473 Reread 15.0234 Random Read 7.41504 Random Write 0.649414
Block Size 512k Write 14.8711 Rewrite 17.9922 Read 28.415 Reread 28.3945 Random Read 27.708 Random Write 0.44043
real 3m50.266s
user 0m0.500s
sys 0m3.990s
You SD card looks to be very slow.
SanDisk figures are OK except for dismal random writes.