Monorepo Frontend · Q&A · Cut our monorepo-frontend-qa build from 4 minutes to 40 seconds with these 5 changes

It took me two weeks of on-and-off digging and plenty of wrong turns. Writing the process down as it happened so the next person spends less time.

What genuinely surprised me was the tail. The average looked great while P99 jumped by an order of magnitude past some threshold. The cause was not monorepo-frontend-qa itself but our upstream connection reuse — the load test traffic was too clean and hid the long-tail requests.