Type Performance

Read packages/effect/typeperf/README.md before adding fixtures, changing the harness, updating thresholds, or running cross-ref comparisons. Isolate one realistic public type path and compare the same fixture and compiler environment across revisions. Derive supported suites and comparison commands from the current harness documentation and CLI.

Before changing a threshold, record its previous value and measured result, explain the expected delta, update it, and run a clean focused verification. Keep ordinary threshold fixtures separate from cross-ref fixtures.

This branch is complete when the focused measurement is repeatable, threshold verification is clean when applicable, and reported comparisons include resolved refs, compiler version, and an explanation of the observed delta. Fixture or harness changes also require the focused validation and formatting checks documented in the README.