Use build profiles to remove expensive work

Measure where build time goes, then remove or replace the compiler work or dependencies responsible for the bottleneck.

Prompt

Evaluate and apply this CI technique to my repository: Use build profiles to remove expensive work.

Measure where build time goes, then remove or replace the compiler work or dependencies responsible for the bottleneck.

Read the technique and its source-backed company examples: https://starsling.dev/ci-playbooks/techniques/profile-build-hotspots.md

Inspect this repository’s CI workflows, build and test commands, dependencies, and recent run timings. Identify where this technique applies and explain the expected benefit using this repository’s evidence.
Measure a baseline from recent comparable runs: elapsed time, queue time, runner minutes and failures where available. If data is unavailable, say what cannot be measured.
Compare relevant company approaches, checking prerequisites, platform differences and tradeoffs. Rank applicable options by evidence, fit and measurable opportunity; do not present company results as predictions for this repo.
Recommend the smallest safe change, show what checks and fallback paths remain, and ASK ME WHICH CHANGE TO APPROVE BEFORE EDITING ANY FILES.
Only after approval, work on a new feature branch, make one reversible change, and open a reviewable pull request. Never merge or push to a default or protected branch.
Keep required checks, test coverage, deployment and release behavior intact. Validate the change and compare equivalent runs where possible; report limitations and what should be monitored after merge.

View all playbooks

How companies used this technique

Read what each company changed and follow the original sources.

Remove the compiler work a profile identifies

Codex removed async-trait wrappers from its concrete tool handlers and kept boxing only at the object-safe registry adapter, after a compiler profile showed where rustc spent its time.

Clean codex-core rebuild: rustc total 187.15s to 68.98s Source

Use it when: Compiler profiles point to one macro, generic construct or module.
Before applying it: Compiler phases overlap, so their timings do not add up. Source refactors need behavior, API, runtime and target checks.

Remove expensive dependencies from the hot build graph

Sorbet replaced a Protobuf-based serialization path with JSON, removed protoc from its main target’s dependency graph, and added a Bazel query to its linters that flags any new path back to protoc.

On a Linux aarch64 developer machine, a debug build of the main target took 3:57.62 before and 2:55.61 after, per the author. Source

Use it when: One target repeatedly compiles a large dependency that an equivalent implementation can avoid.
Before applying it: Keep public behavior, serialization formats and every required test, and keep a graph check so the dependency stays out.

How companies used this technique

Remove the compiler work a profile identifies

Remove expensive dependencies from the hot build graph

Related techniques

Let an agent iterate against one CI metric

Link release builds with a faster linker

Measure the cost of the release build profile

Company Playbooks