The reverse complement program certainly doesn't need unsafe code, but the safe rust version[1] takes 3x the execution time of the unsafe rust version[2]. By comparison the fastest Go version[3] is fairly idiomatic Go without unsafe memory management and takes just 2x the time of the unsafe rust version.

Also, which benchmark did you have in mind when you said unsafe code is mandatory?

[1] http://benchmarksgame.alioth.debian.org/u64q/program.php?tes...

[2] http://benchmarksgame.alioth.debian.org/u64q/program.php?tes...

[3] http://benchmarksgame.alioth.debian.org/u64q/program.php?tes...