Ensure you have a recent C++17-capable compiler and cmake. The below assumes cmake generates Makefiles, however you can use any generator such as Ninja, etc, so long as you place the compiled binary in the fastmine/ subfolder of this project when done.
$ cd fastmine
$ cmake . && make
$ cd ..
Then set in .env
USE_FASTMINE="yes"
Note: In order for fast mining to work, the expectation is that the fastmine executable will be present in the fastmine/ subdirectory.