## Summary
Add a `@perf` test measuring the cost of entering a subgraph containing
80 interior nodes. Establishes a CI baseline for the synchronous
mount/unmount bottleneck.
## Changes
- **What**: Add `subgraph transition (enter and exit)` perf test to
`performance.spec.ts` and a test workflow asset
(`large-subgraph-80-nodes.json`) with a single subgraph node containing
80 Note nodes.
## Review Focus
This is PR 1 of 2. The test establishes a baseline on main so the
optimization PR (PR 2) can show a CI-proven delta for `taskDurationMs`
and `totalBlockingTimeMs`.
The test:
1. Loads the 80-node subgraph workflow
2. Enters and exits once to warm up
3. Measures a fresh enter transition (start → 80 nodes mounted → layout
settled)
4. Records `taskDurationMs`, `layouts`, and `TBT`
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-10480-test-add-perf-test-for-subgraph-transition-bottleneck-32d6d73d3650811b9b6eec03a9591f82)
by [Unito](https://www.unito.io)
---------
Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: Connor Byrne <c.byrne@comfy.org>
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