September 26, 2026
Opus 5.5 rewrote a Rust engine in assembly: up to 17× faster
In open PR #35 from Sep 25, the ASM version of ttfx sped up the `print` effect from 267 to 16 ms: 16.7× on Zen 5. Opus 5.5 ported the engine from Rust to x86-64 assembly in a single pass. The `asm-zen5` branch contains 88 commits.
DHH
@dhh
I ported the Omarchy splash-screen engine (ttfx) from Rust to x86-64 assembly, and it became up to 17 times faster!! Opus 5.5 translated it in one pass. We keep drilling until the agent's drill hits bedrock! https://github.com/omacom/ttfx/pull/35/
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ttfx rendered effects with a Rust engine. In the PR, ASM is enabled automatically only on x86-64-v4 CPUs with AVX-512, while v3 with AVX2 and v1 retain Rust.
The full suite was checked. The author claims support for all 37 effects and their options, including ANSI input, `--wrap-text`, and `--existing-color-handling` modes. The `tools/asm/oracle.sh` script compared stdout, stderr, and the exit code of the Rust and ASM versions across 91,641 cases: 0 errors.
In the author's Zen 5 benchmark with a 200×50 canvas, one core, seed 1, and `--frame-rate 0`, the geometric mean speedup was 4.1×. The `waves` effect dropped from 414 to 27 ms, or 15.3×. The author used the best of five runs for each effect.
Building ASM on x86_64 Linux requires NASM 3.0 or later. The author installs it with `pacman -S nasm`; without NASM, the build will warn and produce a pure Rust version. `TTFX_ASM=0` forces Rust, while `TTFX_ASM=force` requires ASM and exits with code 3 if it fails to start.
PR #35 remains open, so the ASM engine has not yet made it into a release.
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