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An intern used Rust to save TikTok $300k! Yes, you heard that right. Rust’s performance and efficiency are unmatched, and this story proves it.

Original video: https://www.youtube.com/watch?v=sELryGUfzMg

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Chapter:
0:00 Context
0:39 Problem
1:02 Why Rust
1:17 Rewrite Approaches
2:40 Final Solution
3:50 Results
4:24 Takeaways

Let's Get Rusty

A TikTok intern rewrote CPU-intensive payment service endpoints from Go to Rust, reducing average latency by 30%, P99 latency by 76%, and cutting compute costs by 50%—saving $300K annually. The migration used a gradual rollout strategy with separate Rust clusters under the same service name, avoiding upstream code changes. Key challenges included adapting Go's zero values to Rust's Option enum and optimizing memory allocations. The main lesson: Rust delivers performance gains at the cost of developer productivity, making it ideal for high-usage, stable components where economies of scale justify the rewrite effort.

Rust intern saved TikTok $300K

I’m a Go developer and I see value in this argument. 10/10 this is how optimization should be done. Not prematurely but targeted.

Remember kids, when you rewrite something then you can also eliminate the technical debt and inefficiencies that the old program had. When you compare the old program, that has all the technical debt, with the new program (clean and no debt) and from this deduce that the programming language Y is better than X, then you are falling into a pitfall.

That’s seriously impressive. A 30% latency drop and 50% cost reduction is no small feat, especially from an intern! Rewriting performance-critical services in Rust and pulling it off cleanly shows deep technical maturity.

<ol>
<li>Seeing how this intern was so skilled he detected such an issue, he could have fixed it in any language, including the original one</li>
<li>Still impressive and yeah Rust has memory guarantees, as far as the compiler and the unsafe base is correct, that’s pretty appealing if the language weren’t such an eyesore with a million features (personal rant at the end but yeah Rust is awesome I love using software written in it).</li>
</ol>

For which this unpaid slave labourer will receive… nothing, I assume. Internships are a horrid part of modern society.