Rendering Huge Pull Requests in the GitHub Copilot App

2026-09-24

GitHub rebuilt the Copilot app's pull request view to keep a diff with 2,200 files, more than one million changed lines, and over 400 inline comments responsive. The design separates fixed code geometry from lazily measured comment blocks, then uses permanent instrumentation and automated stress loops to catch scroll jumps, leaks, and jank.