I don't think it was true even in 2023.

This sounds like tackling the problems of C++ in the early 2000s.

1. Casey Muratori also that DRY shouldn't doesn't have to result in non-performant code.

2. Smaller functions, functions that do one-thing: Modern compiler can inline those. There are some edge cases where inlining may make less efficient use of states and loops but I don't think that's a main problem nowadays. I also wouldn't say the extreme version of this idea (very small functions) is still popular. The strongest proponent of this was Uncle Bob, and the last time I've heard him speak about code, he said he now lets the LLM write everything and he only reviews the module hierarchy and maybe the modules' public interfaces.

3. Polymorphism instead of ifs and switches was a big fad in the late 1990s until the late 2000s and had some holdouts in the 2010s. It was only ever popular in the Enterprise Java and C++ world (and maybe in Enterprise Smalltalk, never hard). Overuse of runtime polymorphism widely considered bad form in newer static languages like Go and Rust and in most dynamic languages there was always a tacit understanding of "use mostly conditions, add polymorphism if you need extensibility".

In functional languages (or languages heavily influenced by functional programming like Rust, Swift and Kotlin[1]), the classic approach for the type of scenario in this example is to use a sum type, and run a safe exhaustive match/switch on all the variants.

4. Hiding internals: The sum type example is telling of modern best-practices. Sum type fields are generally made public. Some languages (e.g. Rust and most pure functional languages) do not support private fields in sum types at all! Other languages (e.g. Kotlin) but immutable, so it's easy to maintain invariants without hiding information. Sometimes we do want to hide the type details and wrap it with public-facing type (this is a common pattern with internal error enums in Rust for example). Even in this case, there is no impact since we do not use runtime polymorphism or indirection (that would be Box<T> in Rust).

Due to compiler optimizations, hiding internals has marginal performance cost (if any) unless you require runtime polymorphism to achieve it. But why should you?

I feel like the performance costs lamented in this article mostly have to do with runtime polymorphism in static languages. And I fully agree here: runtime polymorphism is something that should be avoided when you don't need it[2]. But that's the thing: if you're looking at modern static language codebases, runtime polymorphism is not as hyped as it used to be in the past. Some languages still require heavy use of runtime polymorphism (Go is a good example of this), but other languages more often rely on static polymorphism (Rust) or compile time duck-typing (Zig and you could argue C++ template meta-programming used to do that, albeit quite awkwardly).

Even with all the issues you get with polymorphism, I don't think it's the main cause of slow application performance. It be very much the culprit in tight loops inside games, but if you look at the performance issues plaguing everyday apps, I think the two major culprits are endless layers of abstraction (the most quintessential example is basically every sluggish Electron app out there) and blocking the user on slow actions (like network loads).

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[1] Even Java had sealed record types for a while now, and I'm sure will see Enterprise frameworks encouraging them in 20 years, when the rest of the world has moved on to spacefaring super-intelligent LLMs. But Enterprise frameworks also don't encourage you to write DRY code or keep your functions short.

[2] But do keep in mind that in Java it could be almost zero-cost in many cases. The JIT will monomorphize or bimorphize your classes if you always use the same class at the same callsite. The pointer indirection is not an extra cost, since every non-primitive that doesn't undergo Scalar Replacement[3] lives on the heap, and has a pointer.

[3] https://shipilev.net/jvm/anatomy-quarks/18-scalar-replacemen...

Nobody argues with that. But it's helpful to know right from the title that it's the original Casey's work and not something newer.

I wish we were at the level where some doofus has red too many "Gang of Four" "Design Patterns OOP" bullshit books and gone to town. Because that would be way better than what we have now.

Whenever I run a thing and it's unbearabily super duper slow, when you look at the process lists the thing will have spawned bunch of chromium instances - on top of probably making bunch of internet connections. Delegating some of the work that can easily done on my PC to "cloud" instead.

What we have now is way worse - it's electron and webshit technologies on desktop. Like you couldn't make software of worse quality even if you tried. The performance way worse than PCs of 1990s. It's almost like using software that's running from a floppy disk.

And now this trash is probably getting generated with LLMs.