Per-call overhead:

  C (baseline)    - ~30 ns
  Rust (unsafe)   - ~30 ns
  C#              - ~30-50 ns
  Go (cgo)        - ~40-60 ns
  Java (JNI)      - ~300-1000 ns
  Python (ctypes) - ~10,000-30,000 ns
  Common Lisp (SBCL) - ~500-1500 ns

As if there is an alternative :)

More seriously, it’s “unsafe” from the perspective of the library calling into C, but usually “safe” for any layer above.

For what it is worth, I asked about LuaJIT after I have shared the link, and the numbers are now different for some languages, albeit not by much. Go (cgo) became ~50-100 ns. That said, I still believe it is unfair to single out Go when it does way better than some other GC languages.

Language/API | Call Overhead (no-op C) | Notes

Go (cgo) | ~40–60 ns | Stack switch + thread pinning

Java FFM | ~50 ns (downcall) | Similar to JNI, can be ~30 ns with isTrivial()

Java FFM (leaf) | ~30–40 ns | Optimized (isTrivial=true)

JNI | ~50–60 ns | Slightly slower than FFM

Rust (unsafe) | ~5–20 ns | Near-zero overhead

C# (P/Invoke) | ~20–50 ns | Depends on marshaling

Python (cffi) | 1000–10000 ns | Orders of magnitude slower |

you can verify this easily with Deno ffi which is pretty much optimal for JS runtimes. also, from everything i have seen and read, luajit should be even lower overhead than this.

you really shouldn't be asking chatgpt questions like this imo. these are facts, that need to be proven, not just vibes.

"ants_everywhere" is right.

The anti-LLM activists that patrol HN will often downvote comments just for stating facts that disagree with their hatred of LLMs.