Wikipedia mentions that Wasm is faster to parse than asm.js, and I'm guessing Wasm might be smaller, but is there any other reason? I don't think there's any reason for asm.js to have resulted in slower execution than Wasm.
Honestly the differences are less than I would have expected, but that article is also nearly a decade old so I would imagine WASM engines have improved a lot since then.
Fundamentally I think asm.js was a fragile hack and WASM is a well-engineered solution.
After reading the, I don't feel convinced abtout the runtime performance advantages of WASM over asm.js. he CPU features mentioned could be added to JS runtimes. Toolchain improvements could go both ways, and I expect asm.js would benefit from JIT improvements over the years.
I agree 100% with the startup time arguments made by the article, though. No way around it if you're going through the typical JS pipeline in the browser.
The argument for better load/store addressing on WASM is solid, and I expect this to have higher impact today than in 2017, due to the huge caches modern CPUs have. But it's hard to know without measuring it, and I don't know how hard it would be to isolate that in a benchmark.
Thank you for linking it. It was a fun read. I hope my post didn't sound adversarial to any arguments you made. I wonder what asm.js could have been if it was formally specified, extended and optimized for, rather than abandoned in favor of WASM.
