November 4, 2025
WASMageddon or Nothing-burger?
WASM 45% slower than Native Code
Slower but Everywhere: Internet Splits Over WebAssembly’s 45% Hit
TLDR: New tests say WebAssembly in browsers runs about 45–55% slower than native apps, with peaks up to 2.5x. Commenters split: some cry “misleading” and note faster ahead-of-time runtimes, others happily pay a “run-everywhere tax,” while optimists expect future CPU tricks to shrink the gap.
Grab your popcorn: a new study says code compiled to WebAssembly runs about 45–55% slower in browsers than “native” desktop apps, with worst cases up to 2.5x. The twist? The comments section isn’t mourning—it’s brawling. One camp yells clickbait, arguing the title ignores faster ahead‑of‑time runtimes outside the browser and that browsers rely on just‑in‑time compilers that aren’t fully optimized yet. Another camp shrugs and says, “45% slower to run everywhere? Deal.” Portability—the same app working on any device—has people treating this like a reasonable “run‑anywhere tax.”
There’s also a wave of surprised optimism: folks expected disaster, not “half‑speed,” with one commenter joking that not even being 10x slower is a win. Developers chime in with hope for upgrades—SIMD (vector tricks for CPUs) and other optimizations could close the gap, and compared to JavaScript (often 2–10x slower), WASM still looks like a glow‑up. A Rust dev admits they’ve seen slowdowns but not 45% in their own projects—cue suspicion that benchmarks vs. real apps tell different stories.
The vibe: headlines scream, but the crowd says context matters. Today’s verdict is “slower but solid,” and the meme of the week is: pay a little speed, get freedom to run anywhere. Tomorrow’s updates might flip the script.
Key Points
- •Researchers built Browsix-Wasm to run unmodified WebAssembly-compiled Unix applications directly in browsers.
- •Using the SPEC CPU suite, WebAssembly showed average slowdowns of 45% (Firefox) and 55% (Chrome) compared to native code.
- •Peak slowdowns reached 2.08× in Firefox and 2.5× in Chrome across the evaluated benchmarks.
- •Performance gaps are attributed to missing optimizations, code generation issues, and inherent WebAssembly platform constraints.
- •Prior evaluations showing ~10% slowdown focused on small kernels; this study assesses more substantial applications with a full Unix-like environment.