Performance methodology

Every performance claim in Reticle is a measured number, not an aspiration. This chapter describes how the numbers are produced so they can be reproduced and trusted; the numbers themselves live in docs/PERF.md.

How measurements are taken

• Microbenchmarks use criterion, which runs each benchmark many times, warms the caches, and reports a statistically meaningful median with a confidence interval. The benchmark inputs come from the deterministic layout generator, so a run is reproducible.
• Frame timing for the renderer is measured with an in-process profiler (puffin) fed by tracing spans, and with the offscreen render harness, which renders scripted camera paths and records per-frame times.
• The host is recorded with every number: these are measured on an RTX 4060 Ti 16 GB. Numbers from other machines are not comparable and are not mixed in.

Guarding against regressions

The benchmark results are committed as a history. xtask perf-check compares a fresh run against the committed baseline and fails if a result regresses beyond a threshold, so a performance regression is caught the same way a test failure is.

Honesty

Where a target is missed, the measured number and the bottleneck are recorded plainly. A missed target with an honest explanation is more useful than a number that cannot be reproduced.