How further/quicker can I make this solution for a fun hackathon?

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Hey :waving_hand: I am new-comer into the language which came to my knowledge while contributing to LavinMQ.

The first opportunity for me to understand the language more deeply is the Brazilian Brawl - an annual country-wide hackathon 4fun with backend challenges. This year the challenge is to write an API that can integrate with another API by which may or may-not be failing.

It’s a great exercise for overall engineering and it’s all allowed.

I am asking wether anyone want’s to nerd about much I can push forward for performance using Crystal.

Limitations:

  • Use only 350MB RAM
  • Use only 1.5vCPU
  • Needs 1 LB
  • Needs 2 Apps
  • Total amount of requests + processed $$ should be consistent with your backend + the processors.

My current solution and performance-points:

  • Crystal 1.17
  • Write API
  • Read API + Worker to integrate/call external APIs.
  • The worker stores in-memory SkipList to run RANGE queries with SUM
  • NGINX load balances writes and ponts READS into the worker.

My code repo: GitHub - lukas8219/rinha-de-backend-2025: Crystal, LavinMQ, NGINX, Circuit Breaker

What I wanted to ask and discuss:

  • How fast can I make the p99?
  • Is there any clear performance issues with my code regarding Crystal best practices?
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2

Hi Lucas!

I believe it will be easier for the community members if you can first share more data from real execution of your code.

What are your current results?

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Hii Paulo! Thanks for reaching out.

Let me grab more statistical data. I do have the current results here which are satisfactory but yet a bit inconsistent. I figure it might be something else instead of Crystal so let me dive into it before sharing any numbers and more data