🤖

Series · Part 14 of 21

Practice
AI Demystified
Abhishek Saha
Abhishek Saha
· 🤖 AI / ML

Latency, Tokens, and Cost — The Physics of AI Products

Why is AI slow? Why does it cost money? What does streaming actually change? The mechanics of inference, visualized.

Latency, Tokens, and Cost — The Physics of AI Products

Every AI API call has a cost and a latency. Neither is random — they follow directly from how inference works. Understanding the mechanics means you can optimize before the bill arrives.

VISUAL EXPLAINER
Inference: Cost & Performance
INPUT TOKENS500
API CALL TIMELINE
Network
Queue
Prefill
Generation
⬡ first token
round trip to datacenter
waiting behind other requests
processing your input tokens
generating output tokens, one at a time
TTFT
0ms
Tokens/sec
0
Output tokens
0
Total latency
0ms
PHASE BREAKDOWN
Network
0ms
Queue
0ms
Prefill
0ms
Generation
0ms

The first optimization is always streaming — it doesn’t change total latency, it changes perceived latency. Users see text in 300ms instead of 4 seconds, for free.

Next up: You can run great AI cheaply. Part 15 covers the harder question: how do you know it’s actually working correctly?

AI Demystified · 16 of 21 published

  1. 0 Grounding 5 Mental Models You Need Before Diving Into AI
  2. 1 Foundation What Happens When You Ask AI Something?
  3. 2 Foundation Transformers — The Architecture That Changed Everything
  4. 3 Foundation How AI Learns, Thinks, and Decides
  5. 4 Foundation How AI Reads Your Words
  6. 5 Foundation Why AI Forgets
  7. 6 Foundation Why AI Lies (And Doesn't Know It)
  8. 7 Foundation What AI Cannot Do
  9. 8 Foundation How AI Reasons (And Why It Sometimes Breaks)
  10. 9 Practice Prompt Engineering — How to Talk to AI
  11. 10 Practice Embeddings & Vector Databases — The Memory Layer of AI
  12. 11 Practice RAG Explained — How AI Knows What You Didn't Train It On
  13. 12 Practice Fine-tuning vs. Prompting — When to Use Which
  14. 13 Practice Do You Really Need GPT-4?
  15. 14 Practice Latency, Tokens, and Cost — The Physics of AI Products
  16. 15 Practice How Do You Know AI Is Actually Working?
  17. 16 Hands-On Coding Setup — Your AI Development Environment soon
  18. 17 Hands-On MCP Tool Calling — How AI Uses Tools soon
  19. 18 Hands-On AI Agents — Beyond Chatbots soon
  20. 19 Hands-On Build Your First Real AI App soon
  21. 20 Hands-On Token Optimization — Spend Less, Get More soon
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