Microsoft has a C++ API you use to make programs for windows. If you write in C++ you will code directly against that. If you write in Javascript then you will code against someone else's API that they wrote to interface with the Microsoft API. If you write in Javascript another step up then you will code your plugin against the VSCode API which then uses the Electrons wrapper around Microsofts API to do stuff, if there aren't more libraries in between. This stack of abstractions turned out to be too slow to solve the problem mentioned in the article we are talking about, so to solve it they moved the entire thing up one step in the stack.

In these situations it is common to have a problem that is really easy to solve but the API abstractions you have to work with doesn't support the operations at the speeds you need to solve it. If you have never experienced that then you aren't working on performance intensive projects where every bit counts and your input on this topic doesn't matter. I have worked on performance intensive libraries crossing programming language boundaries and the abstraction boundaries absolutely puts a limit on the amount of performance you can get. Well designed abstractions are less obstructive but plenty of them aren't well designed and even the well designed ones have overhead.