---
title: "Casey Destroys Optimization Myths | TheStandup"
url: https://daily.dev/posts/casey-destroys-optimization-myths-thestandup-yqbdazrnn
source_url: https://www.youtube.com/watch?v=pslodI0Mh_0
type: video:youtube
source: "ThePrimeTime"
published: 2026-06-07T13:25:40.432Z
updated: 2026-06-07T13:33:05.053Z
tags: ["performance", "architecture"]
reading_time: 28
upvotes: 34
comments: 4
language: en
---

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# Casey Destroys Optimization Myths | TheStandup

**[ThePrimeTime](https://daily.dev/sources/primeagen)** · 28 min read · 34 upvotes · 4 comments

## Summary

Casey debunks a viral tweet claiming that replacing division with reciprocal multiplication always improves performance. Key points: (1) floating-point division and multiplication are not mathematically equivalent due to precision loss, which can matter in scientific computing; (2) modern CPUs (e.g., Zen 4/5) handle floating-point division far faster than the tweet's claimed 20–40 cycles — closer to 3–10 cycles latency, with throughput of 2–3 cycles vs. 0.5 for multiply; (3) in a load-op-store loop, the bottleneck is usually memory bandwidth, not the arithmetic operation itself, making the divide-vs-multiply distinction largely irrelevant; (4) blindly applying such micro-optimizations without profiling and understanding the full pipeline leads to wasted effort and incorrect mental models about performance.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://www.youtube.com/watch?v=pslodI0Mh_0>

## Community discussion

Top comments from developers on daily.dev.

**@ambi\_dex** · 1 upvotes

> I liked this video alot. I find CPU architecture to be very interesting and Casey's explanation of the deeper understand into the reason for using it and why you may want to use it when looking at the over all picture and putting it under a real test and not look at it like.. Heres a for loop and it does this div operation and be simplified if you multiply instead since its supposed to be less steps over all compared to div steps. Like Casey says - 10-30 cpu cycles which he active proves that , that is like old old CPU architecture and Zen 4 architecture handles dividing waaay better as well...

**@hanzo** · 1 upvotes

> Casey-chad

**@ajaychoudhary80** · 0 upvotes

> Most performance myths ignore the actual bottleneck.

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---

Tags: [#performance](https://daily.dev/tags/performance), [#architecture](https://daily.dev/tags/architecture)

[View this post on daily.dev](https://daily.dev/posts/casey-destroys-optimization-myths-thestandup-yqbdazrnn)