I don't believe this, but it's an understandable error. First, let me be clear that handwritten optimized WASM is faster and smaller than heavily optimized Jav

I don't believe this, but it's an understandable error. First, let me be clear that handwritten optimized WASM is faster and smaller than heavily optimized Javascript on primitive types, by significant margins. It doesn't surprise me that compilers burn this (to put it mildly, compilers aren't great at code generation), but it's worth noting that the raw throughput difference is there and definitely measurable. This difference should be expected to grow in the near future, since browsers' WASM compilers are suboptimal right now. Now, more importantly, the major criticism I have with this is that it is presumably focused on small imperative tasks, which ignores the main places performance is lost in a language like Javascript: 1. Javascript can't handle memory efficiently without doing everything through typed arrays. Efficient use of memory (compact representations, mutation and sharing, sequential access, etc.) is an unreasonable task in a high level language, whereas transpiling to WASM works. 2. Javascript's abstractions are heavy and inefficient. Building your own abstractions is liable to have similar issues. A language like C, C++, or Rust lets you build efficient abstractions both in the small ("zero-cost abstractions") and in the large (architecturally). Little unpublished demos won't show that.