is there a SD card read/write test and variable overclock setting?
Found a benchmarking test/tool on RPi that might help
https://www.jeffgeerling.com/blog/2016/how-overclock-microsd-card-reader-on-raspberry-pi-3
Here is a script from that above site that might help, if you can pick thru it
http://www.nmacleod.com/public/sdbench.sh