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In principle, Javascript on modern JIT can approach roughly 40-80% of the performance of C++, more or less across the board, not just in some toy benchmark. Thi

In principle, Javascript on modern JIT can approach roughly 40-80% of the performance of C++, more or less across the board, not just in some toy benchmark. This benchmark is from 2014: https://blogs.unity3d.com/2014/10/07/benchmarking-unity-performance-in-webgl/ https://blogs.unity3d.com/2014/10/07/benchmarking-unity-perf... Granted, this benchmark is for generated Javascript, not "idiomatic Javascript" (if there is such a thing). Of course you can write arbitrarily slow Javascript as well. There's a lot of stuff that can throw a wrench into the JIT.

mattmanser 6y ago
That seems an optimistic reading of those graphs. As far as I can tell. a lot of them are 20-30% the speed of native, not 40-60%.
- gridlockd 6y ago
  For the Firefox graph, none of them are below 35%, only three are below 40%. The average is well above 60%. That said, there's a lot going on there. Javascript can not use SIMD or multiple threads. Some tests are heavier on C#, which is converted to C++ in the Javascript version and thus becomes "faster than native C#". The point is not give an exact number on how fast Javascript is compared to any other language, there's wide variance across usage and implementations. The point is to show that Javascript to rival C# performance is feasible.