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.
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.