utils.fast_safe_load already exists, is pinned by tests/test_fast_safe_load.py, and
its comment names exactly these payers: 'startup parses config.yaml and every plugin
manifest, so the slow path cost ~0.9 s of cold start'. The migration was started —
hermes_cli/config.py uses it eight times, hermes_cli/main.py and hermes_cli/plugins.py
too — but the file-level loaders it was written for were never converted.
The cost is config SIZE, and the size is the installer's doing: it seeds config.yaml
by copying cli-config.yaml.example, 120,897 bytes of mostly comments. Nothing caches
load_gateway_config() and it has 238 production call sites.
Profiled before assuming a cause — reader.forward 34 ms, scanner.scan_to_next_token
28 ms, reader.peek 13 ms: the pure-Python PyYAML scanner, nothing else.
Measured A/B on one realistic pass (gateway config + every bundled plugin
description), medians of five runs, __pycache__ cleared between arms:
48.8 ms -> 2.46 ms. Per path: load_gateway_config 48.3 -> 1.84 ms, managed
config.yaml 44.4 -> 1.03 ms, 105 plugin.yaml manifests 59.3 -> 5.9 ms.
Same parse, same restricted tag set, same result — only the loader changes. Drops the
three 'import yaml' statements the swap orphaned.
(cherry picked from commit a4efd6a4506043159310eba02c32b673c455b88b)
16db511ed5