alt Hacker NewsI tried it on my primes micro-benchmark (http://hoult.org/primes.txt) and got a 2:1 slowdown on 13th gen i9.
It does a LOT of array access and updating, probably near to worst-case for code that isn't just a loop copying bytes.
The average slowdown is probably more in the same region as using Java or C# or for that matter C++ std::array or std:vector.
If you missed it, djb himself posted this cute graph of "nearly 9000 microbenchmarks of Fil-C vs. clang on cryptographic software (each run pinned to 1 core on the same Zen 4)":
https://cr.yp.to/2025/20251028-filcc-vs-clang.html
I've heard Filip has some ideas about optimizing array performance to avoid capability checks on every access... doing that thread safely seems like an interesting challenge but I guess there are ways!