Since version 6.2.0, FastTrack has been compilated using MinGW_w64 instead of MSVC2019. MinGW_w64 is a fork of the MinGW project that provides the GCC compiler for Windows. With a "better-conforming and faster math support compared to VisualStudio's" and a pthreads library, this compiler yields better performance for the OpenCV library and thus for FastTrack.
Compiling FastTrack using MinGW_w64 provides several improvements. First, it provides the getopt.h header necessary to the FastTrack-Cli. From version 6.2.0, the command line interface of FastTrack is available natively on Windows. Secondly, OpenCV compiled using MinGW_w64 is more performant than with MSVC and Qt seems more responsive. Finally, the bundle (executable plus DLLs) is lighter than its MSVC counterpart (42,7 MB vs 62.8 MB).
Compiling FastTrack using MinGW_w64 comes with some challenges. The main dependency of FastTrack is OpenCV and it does not provide pre-built binaries for MinGW_w64, therefore, we need to compile OpenCV from sources. This compilation is done one time in this GitHub repository and files are downloaded at compile time to save processing energy. Conveniently, Qt provides pre-built binaries and the whole MinGW_w64 toolchains in its archives. Installing Qt and MinWG_w64 can be done very easily without external sources. The windeployqt Qt tool takes care of the DLLs (Qt and MinGW_x64) needed at runtime and the resulting bundle is very light. MinGW_w64 version of Qt does not provide the QtWebEngine, thus, the in software documentation is not available anymore.
To conclude, MinGW_w64 version of FastTrack has better performance, a lighter footprint with only one drawback: recompile OpenCV when newer versions will be available. For developers, the environment is easier to set up with only three commands necessary.