Re: interpreted, dynamically typed crap like JavaScript and TypeScript are slow...
No. The article is talking about compile time, not run time. In TypeScript that's when the type checks happen.
In fact, fuck it, here's what copilot has to say:
Modern JavaScript implementations are extremely efficient—far more than many developers realise.
In the early 2000s, JavaScript was mostly interpreted and relatively slow. Today, engines such as:
V8 (Chrome, Edge, Node.js)
SpiderMonkey (Firefox)
JavaScriptCore (Safari)
use sophisticated JIT (Just-In-Time) compilers, multiple optimisation tiers, inline caches, type specialisation, and advanced machine-code generation.
Hot code paths that run repeatedly can be optimised into highly efficient native machine code. V8's TurboFan compiler and Firefox's optimising tiers specifically target frequently executed code.