W-243 step 3 profile: which unit tests start a subprocess. macOS, pytest -n auto, tests/,
working tree of 2026-09-30 before the test_sr_freshness change. Test CALL time only.
Method: a -p plugin wrapping subprocess.Popen.__init__, counting per test.

tests run: 6462   total call time: 338 s
tests that spawn: 554   their call time: 170 s (50 %)   spawns: 2879

spawns  tests  call_s  file
  1551      6    29.3  tests/test_sr_freshness.py
   264     98    12.0  tests/test_doctor.py
   189     10    16.4  tests/query/test_authority_prior.py
   112      5     2.7  tests/test_sr_owns_hash.py
    51     10    11.1  tests/query/test_mined.py
    47      7    11.6  tests/query/test_intent_prior.py
    47     47     3.0  tests/test_golden_traversal_guard.py
    39     12     2.0  tests/maintain/test_hooks.py
    35     32     1.8  tests/test_golden_key_guards.py
    35     23     3.5  tests/ingest/test_skipnotice.py
    34     20     2.4  tests/ingest/test_delta.py
    33     11     6.2  tests/query/test_anchor_node_twin.py
    31     11     1.5  tests/test_doctor_url_decoders.py
    29     16     3.9  tests/maintain/test_runner.py
    27     18     3.3  tests/ingest/test_urlsrc.py
    27     12     2.1  tests/test_doctor_fetcher_routes.py
    23     13     2.1  tests/enrich/test_doc2query.py
    20     12     1.6  tests/ingest/test_url_reredaction.py
    20      9     2.6  tests/test_confidence_floor_off.py
    18     18     1.1  tests/test_golden_hook_prose.py
    18      8     2.9  tests/test_commit_paths.py
    17      9     1.2  tests/ingest/test_run.py
    17     13     1.7  tests/ingest/test_ingestlog.py
    17     10     2.0  tests/test_node_bundle.py
    16     10     0.8  tests/ingest/test_carry_forward_invalidation.py
    11      1     2.6  tests/test_golden_history.py
    11      6     2.8  tests/query/test_rm3.py
    10      9     0.6  tests/test_record_components.py
    10      7     1.2  tests/test_url_update_policy.py
     9      1     0.2  tests/test_golden_switch.py

Windows (CI job 109731811596, py3.12): unit 218 s for 6 269 tests; slowest was
tests/test_sr_freshness.py::test_no_behaviour_change_landed_without_its_adr at 71.92 s
(Linux py3.13 in the same run: 10.37 s).

test_sr_freshness.py git spawns by command, one run of the history test:
  before: rev-parse 2, log 87, show <blob> 724, show --name-only 63, show --unified=0 663
  after:  rev-parse 3, log 88, show --name-only 63, show --unified=0 41, + one cat-file --batch
  the history test alone, locally, same loaded machine: 23.65 s before, 5.91 s after
