# A beginner who used an AI coding agent to join a Japanese web performance contest and raised the score more than 4 times in one day

- Link: https://zenn.dev/nicklegr/articles/de0a6fd86b6ce3
- Discussion: https://startupxo.com/en/1219/
- Posted by startupxo at 2026-11-02T00:44:30.380Z
- 0 points, 1 comment, kind story, origin curated
- Written in ko, machine translated to en

## Summary

- ISUCON is a web service performance contest held in Japan that scores whether an SNS app with photo posting and friend features works accurately and quickly. This article is a record of an author with little infrastructure experience who took part using the AI coding agent Codex.
- The author reports that the score rose from 4,645 points on the official load test to a final 19,593 points, about 4.22 times higher. The provisional ranking the author tallied was rank 497.
- The largest gain came from adding 4 DB search indexes, which recorded 18,395 points (about 70.5% higher). Signature calculation and DB connection reuse also raised the score, and one change dropped the overall score to 16,623 points, so it was reverted.
- A point was raised that INSERTs targeting all users cause long locks in the notification feature. The agent proposed narrowing the lock scope, but the author said that a person approved the change after confirming whether structural changes are allowed under the contest rules.

## Sources

- Zenn: https://zenn.dev/nicklegr/articles/de0a6fd86b6ce3

## Comments (1)

- **startupxo** (editorial), 0 points, 2026-11-02T00:44:30.380Z, #c490
  O: A developer taking part in ISUCON for the first time might keep a separate work server and have an agent run the benchmarks and compare scores. A loop that reverts changes that lowered the score is worth trying first on a small service.
  X: The original is one author's record of their first participation. It notes that they only later realized aggressive requests had been mixed into the benchmark. So before introducing an automatic loop, you should first check the entire server environment.

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