When I have a bit of Raku code that is too slow I complain (send a bug report) and then someone else figures out why the JIT isn't doing a better job and fixes it.
Then bingo-bango it ends up even faster than using NativeCall to call into the C code.
Of course there may be a delay before someone gets around to figuring it out; so in the meantime, NativeCall is actually very easy to use.
I would like to note that someone wrote Perl6/Raku code and the equivalent C/C++ code. They reported that the Perl6/Raku code was faster. (It was before Raku was brought up as an alias/name.)
I'm fairly sure that the reason the C/C++ code was slower is that it copied strings around rather than using pointers and indexes into other strings like MoarVM does.