Comments by "IIIRattleHeadIII" (@badass6300) on "ThePrimeTime" channel.

It needs to be pruned and modernized, not killed. x86-64 is still very backwards compatible and supports a ton of legacy instructions, while ARM gets pruned with almost every new version.
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@betag24cn From what I've read, ARM8 and ARM9 CPUs don't natively run ARM7 and lower code, so they do indeed prune it. And a lot of software requires higher versions of android for a reason. On top of that I've written software for android and versions matter a lot.
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@betag24cn Even x86-64 isn't fully backwards compatible either, x86-64-V3 lost some compatibility with some older programs, especially Windows 1 to 3.1 programs and even some 95-XP programs. ARM CPUs can be just as powerful as x86-64 CPUs, the reason they often haven't been was that they were meant to consume 2-5W and be in battery powered smartphones, but go look at the Snapdragon X Elite or Apple's M3 chips and you will see how powerful they can be, even though Apple's M3 chips are giant, so yeah it's expected for them to be powerful. And technically Apple's M3 is for desktop. On top of that the Snapdragon X Elite will have a 120W version and I don't see that going into laptops, but in mini-PCs and pre-built systems for sure.
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@betag24cn ARM is efficient, exactly because they don't have legacy instructions which add a ton of transistors, overhead and thus power consumption. RISC-V is even more power efficient btw. It's just very young.
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@betag24cn when it comes to Floating Point and SIMD instructions ARM has about the same as x86-64, for the Integer portion they are simpler instructions, but they do less work per instruction so you need more of them, and it balances out. It's the decoders and fetches that are the problem, again since x86-64 needs to be able to decode a ton of legacy instructions the decoders need more transistors and more power to do so, while ARM is very lean and not backwards compatible so the decoders are smaller.
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