If one would like to contribute to Badger, happy to help someone dig deeper in this direction.
sudo apt-get install libaio1 libaio-dev.
I think the best bet is to build a fio equivalent in Go (shouldn't take more than a couple of hours), and see if it can achieve the same throughput as fio itself. That can help figure out how slow is Go compared to using libaio directly via C.
See this issue: