One further note: compiling with -ffast-math is disallowed by react_juce:
51%] Building CXX object src/CMakeFiles/Os251.dir//lib/react-juce/react_juce/react_juce.cpp.o In file included from /media/shcd/dev/OS-251/lib/react-juce/react_juce/./duktape/src-noline/duktape.h:195, from /media/shcd/dev/OS-251/lib/react-juce/react_juce/./duktape/src-noline/duktape.c:188, from /media/shcd/dev/OS-251/lib/react-juce/react_juce/core/EcmascriptEngine.cpp:67, from /media/shcd/dev/OS-251/lib/react-juce/react_juce/react_juce.cpp:78: /media/shcd/dev/OS-251/lib/react-juce/react_juce/./duktape/src-noline/duk_config.h:2861:2: error: #error __FAST_MATH defined, refusing to compile
which is a bit a pity as it typically speed up the DSP considerably...
It makes DSP faster, but cannot be used now.
https://github.com/utokusa/OS-251/issues/15#issuecomment-913148990
Maybe I can try to use Hermes instead of Duktape