You are throttling yourself:
innodb_io_capacity = 100 <-- change to default 200
tmp_table_size = 4G <-- The actual value used will be the smaller
max_heap_table_size = 8G <-- of these two. You should make them the same.
sync_binlog = 1 <-- causes LOTS of disk IO. You should set to 1000 so it syncs less often