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> Is the performance difference of Python and Javascript due to the language or due to the runtime? It's almost always the runtime. Unless the language spec m

> Is the performance difference of Python and Javascript due to the language or due to the runtime? It's almost always the runtime. Unless the language spec makes it particularly difficult to implement a feature in a way that's performant while still respecting the spec. Which is why the discussion on which languages are "faster" is seldom productive. Languages are not fast or slow by themselves. And, even when they are on average, implementing stuff on Assembly is no guarantee of speed. Quite often, higher level abstractions lead to optimizations that are difficult to replicate if one is operating at a lower level. As a very trivial example, consider short circuit evaluation. It's something that you explicitly have to code in assembly, but most languages have implemented out of the box. Or garbage collection - allocating and deallocating memory on demand is memory efficient, but it's not necessarily what you want to do for performance. In many cases, deferring garbage collection allows for often-accessed memory to be retained, where as a C implementation would be constantly allocating and freeing. Fixing that requires programmer effort. What I think matters the most is the ability of a language (+runtime) to access lower layers when needed (ASM blocks in C, FFI in Python).

DeathArrow 4y ago
>And, even when they are on average, implementing stuff on Assembly is no guarantee of speed. Quite often, higher level abstractions lead to optimizations that are difficult to replicate if one is operating at a lower level. When browsing Code Golf, most often than not, the fastest implementation is in assembler. And sometimes it can be 2x - 4x faster than next fastest implementation which usually is C++.
gpderetta 4y ago
While with enough trust even pigs can fly (witness the heroic efforts to make JS fast), some languages are indeed inherently faster than others either because the semantics are such that they are easier to translate to an actual machine efficiently or there is less abstraction between the language and the machine.

DeathArrow 4y ago

>And, even when they are on average, implementing stuff on Assembly is no guarantee of speed. Quite often, higher level abstractions lead to optimizations that are difficult to replicate if one is operating at a lower level. When browsing Code Golf, most often than not, the fastest implementation is in assembler. And sometimes it can be 2x - 4x faster than next fastest implementation which usually is C++.

gpderetta 4y ago

While with enough trust even pigs can fly (witness the heroic efforts to make JS fast), some languages are indeed inherently faster than others either because the semantics are such that they are easier to translate to an actual machine efficiently or there is less abstraction between the language and the machine.