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Full-stack engineer building AI-powered systems. Open to opportunities in Europe.

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© 2026 Eiji Mitsumizo.

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—Career

Video-Listing API ~30× Speedup

PeriodOct 2022 – Mar 2023
RoleSole API developer + load-testing ownership

Made a high-traffic video-listing API ~30× faster with an in-memory DTO cache

Video-Listing API ~30× Speedup — Career

01Overview

Noticing the API's read-heavy / write-rare access pattern, I redesigned it to keep DTOs in memory and let the API only filter them. The result was a roughly 30× speedup on a high-traffic API, released with zero defects. I owned load testing end-to-end — from planning to execution and analysis.

02Highlights

  • Made a high-traffic API ~30× faster, released with zero defects
  • In-memory DTO cache design targeting a read-heavy/write-rare pattern
  • Owned load testing end-to-end — planning, execution, and analysis

03Tech Stack

JavaSpring BootSQL ServerIn-Memory CachejMeter

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