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Why your website should be under 14kB in size

2025-08-03 Science & Technology
394.4k
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ThePrimeTime
ThePrimeTime
1.1m subscribers

Optimizing Web Performance Through TCP Slow Start and the 14KB Limit

Achieve dramatic loading speed improvements by manipulating network initial congestion controls. Understanding TCP Slow Start directly dictates how quickly your users see content, especially on challenging networks.

Short Summary

  • Calculate significant loading time savings (up to 612ms) by keeping initial website payloads under 14 kilobytes.
  • TCP Slow Start governs initial data transmission, iteratively testing network capacity via Acknowledgements (ACKs).
  • Latency, not just bandwidth, severely penalizes users on high-latency links like satellite connections.
  • Applying this initial data constraint remains critical even when using modern protocols like HTTP/3 (QUIC).

This discussion breaks down the Transmission Control Protocol (TCP) fundamentals, focusing specifically on the Slow Start algorithm servers use to estimate network bandwidth during the initial connection handshake. Mastering this concept allows developers to prioritize critical resources so that the first 14KB transmitted provides immediate, useful rendering for the visitor, maximizing perceived performance regardless of modern protocol adoption.

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Description

Twitch https://twitch.tv/ThePrimeagen Discord https://discord.gg/ThePrimeagen Become Backend Dev: https://boot.dev/prime (plus i make courses for them) This is also the best way to support me is to support yourself becoming a better backend engineer. ### LINKS https://endtimes.dev/why-your-website-should-be-under-14kb-in-size/ Great News? Want me to research and create video????: https://www.reddit.com/r/ThePrimeagen Kinesis Advantage 360: https://bit.ly/Prime-Kinesis

Top Comments (10)

@Roman_4x5 2025-08-03

Working on optimization of experience for users on satellite internet, I can tell that most of the web devs have no clue about networking. Today's internet bandwidth is mostly consumed by a bloat.

2.6k 55 replies
@deniskhafizov6827 2025-08-03

remember that Apple website that was essentially empty but contained a background image of over 30Mb in size.

1.2k 13 replies
@themore-you-know 2025-08-03

I've optimized my website under 1kb. It reads: "<under construction, 2001>"

1.0k 7 replies
@claythefoxx 2025-08-03

Big websites are a form of protection from ai scrapers cause there won’t be enough memory on an OpenAI server for a 192gb react webpage

932 20 replies
@Necessarius 2025-08-03

Yeah but they now love react and 4gb of js libs

870 38 replies
@slart1bartfast587 2025-08-03

I have not the slightest clue about web development (am only self-taught hobby programmer doing mostly maths related stuff in C/C++), but I know that somewhere we have taken a wrong turn when I open a newspage and it takes like 3-4 seconds to build up the page with 100Mbps internet connection.

642 23 replies
@RichardRemer-u8o 2025-08-03

Just remember, if you're serving third party ads, nothing you do will make your page perform well.

457 10 replies
@michaelrichey8516 2025-08-03

"we should have always been counting bytes" - absolutely. Back in the day, when storage was at a premium, every byte counted - we wrote programs for all three types of efficiency: compute, transmission, and storage. within 14k - sure, definitely do-able. Looking at my own site, my homepage is 22kB and I'm already identifying ways to bring that down - 33% seems do-able.

371 12 replies
@SidTheITGuy 2025-08-03

damn, that font style in orange color made me think I'm tripping.

278 4 replies
@sK0pe-d9b 2025-08-04

My C Professor wrote the entire CS page for the University in C. It never died and loaded immediately but looked like like it was from the 90s

277 27 replies

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