Skill: Octane performance audit

Skill: Octane performance audit

Use this to investigate performance regressions, benchmark results, scheduler/reconciler overhead, compiler output quality, or ecosystem binding perf.

Read first

• Benchmark README in the affected benchmarks/* directory
• packages/octane/src/runtime.ts comments for runtime-level changes
• Existing benchmark scripts in benchmarks/*/package.json and run.mjs
• The discipline reference for each dimension the change touches: V8 shapes and allocation, DOM work, and scheduling

Hot-path discipline

These rules apply to code that runs per render, node, item, event, signal notification, or server request. Each reference cites the runtime code that already follows the rule.

• Shapes: allocate hot records from one constructor or one literal site with every field present, in a fixed order, as BlockImpl and the bagN factories do. No delete, conditional keys, runtime class fields on hot classes, or per-instance freezing. Keep call sites and return shapes monomorphic, numeric fields integral, and arrays packed. Do not allocate closures, literals, rest arrays, or iterators per item.
• Reachability: never name a heavy function from a hot compiled path. Put feature-only code behind the capability or driver that owns it.
• Member reads: look for repeated property reads and member-chain prefixes in hot code and emitted JS. Prefer a local const for a stable value used more than once; follow Reuse stable member reads.
• DOM: read geometry before writing, never in the render walk, and never interleaved with writes in a loop. Insert built subtrees once. Keep events native and delegated. Write from resize callbacks only through createResizeObserver.
• Scheduling: a microtask, await of a settled value, or requestAnimationFrame is not a yield. Do not add a render or commit per microtask hop. Coalesce first, then yield by posting a task through an existing poster. Leave the documented scheduler contract to issue #1864.