Performance of WebAssembly Runtimes in 2026

pmkary 4 days ago |

Many moons ago I was preparing for an interview to join wasmer, back then they showed me that by running wasmer as a kernel extension in Linux they have made it run four orders of magnitude (10,000 times) faster. Given the WASI, I keep thinking more than the plugin usability of things like wasmer, what is the point of WASM not being accepted as a second binary in all operating systems? Windows could support .exe as well as .wasm for example and we would finally have a cross-plaform binary. Apple would never accept; Microsoft will do, and Linux can simply have,

jezek2 4 days ago | |

Such speedup is not plausible at all. It had to be a flawed benchmark relying on some API being very slow in userspace (probably on purpose, not using it the right way). The raw execution speed of WASM can't change much just because it is in a kernel.

Defletter 4 days ago | | |

That's probable, though if we want to give them the benefit of the doubt, it could be a non-optimised benchmark, ie, something that may be written during the average devoper might ordinarily write, rather than hyper-optimised code specifically for that benchmark.

pmkary 4 days ago | | |

What they had done was wiring kernel level operations, without any of the userspace security checks into the wasmer. Their logic was that given the sandbox of wasmer; what would happen if you removed the sandbox of the OS? And I remember their article was featured in HN for two days or so as well. It was interesting. It wasn't that WASM ran faster than C, it was the API calls. And I keep wondering about an architecture where you have a highly sandboxed universal assembly with some API hardening; a middle ground, and so imagine an app that ran everywhere and was 10~100 times faster. Could be really cool.

jezek2 3 days ago | | |

Yes, it's not a new idea. See Microsoft Singularity research OS for a more recent example.

You would still have slower than native execution speed, security problems with Spectre attacks (in HW process isolation it's avoided by not having other memory mapped at all, other mitigations exist but they cost a lot of performance).

Syscall speedups affect only specific programs or stupidly written SW like some games that are checking current time many many times per frame.

GrayShade 3 days ago | | |

It's not just syscalls. If you trust all of the running code, you can use a single address space for all applications and even the kernel, which lets you avoid TLB flushes.

Whether that's still a good idea given Spectre is another question.

azakai 4 days ago |

Judging by the slow speed of node here, I wonder if it was run without forcing optimizations. It doesn't do OSR (on-stack replacement), meaning that a benchmark script doesn't get a chance to tier up from the baseline compiler to the fully optimized tier.

Running with

node --no-liftoff

avoids this problem.

(This is not an issue on the Web, where code must return to the event loop anyhow, allowing tiering up to work, and node is optimized for that kind of workflow.)

jauntywundrkind 4 days ago |

It'd be nice to see memory use. Ideally base usage, then cost of running 1 of a thing, then cost of running 50 if a thing.

Personally low my 50% speed vs native does not sound like the worst to me. I've spent years using perl, java (in v4-v7 days), node... These have various ways they are less good than native, and we collectively seem to accept that. Ideally yes wasm gets faster but a 2x is pretty ok!

fiiisssh 4 days ago |

We have some more comprehensive benchmarks at https://r-carissimi.github.io/wasure/, with fairly different results.

libsodium is very numeric operation heavy IIRC

josephg 4 days ago | |

What are the numbers in that table? Is higher better or is higher worse? How does fully native C compare? What options are you using?

Edit: ah, higher numbers are better. But that fact is hidden way down in a block of text behind a collapsed details view.

antonvs 4 days ago | | |

Was there a sign saying “beware of the leopard”?

ncruces 4 days ago |

Curious where my wasm2go would stand compared to wazero. I should test it myself. :)

https://github.com/ncruces/wasm2go

gregfurman 4 days ago | |

Seconding this as a brilliant project!

Shameless self promotion here but I’m currently using wasm2go to build a native Go runtime for MicroPython https://github.com/gregfurman/micropython-go

ncruces 4 days ago | | |

Thanks for the kind words!

Added you to my users page a couple days ago, hope you don't mind: https://github.com/ncruces/wasm2go/blob/main/USERS.md

1matin 4 days ago |

It's genuinely great to see WASM runtimes are getting closer to native code while being sandboxed, but these benchmarks assume you're not bundling a whole Runtime + GC + stdlib inside the sandbox.

ashvardanian 4 days ago |

One fairly revealing microbenchmark for WASM runtimes is `int8` dot products & angular/cosine distances.

(My) NumKong [1] has implementations targeting both vanilla AVX2/Haswell and AVX2-VNNI/Alder Lake, which makes it easy to see where runtimes and code generators leave performance on the table.

I started a few Wasmtime/Cranelift PRs around this, but didn’t manage to finish them :facepalm: Might be a fun weekend project for someone interested in backend/codegen work.

[1]: https://github.com/ashvardanian/NumKong

westurner 4 days ago |

WAVM in Rust? WAVM does not yet support ARM MTE or RISC-V CHERI?

wasmtime-mte could be added to the benchmark.