audit-agent-speed — Make the agent setup fast again

Degree of freedom: MIXED — measurement commands [LOW freedom — run exactly]; which fixes to recommend [HIGH freedom].

Audit-and-fix exception. Report first, then fix. Apply local, reversible fixes right away. Ask before anything that needs admin rights, touches committed config, deletes data, or changes a user preference (effort, model).

Most of an agent's turn is model time on the provider's servers, and no local tuning changes that. This skill wins back the local part: hooks, tools, builds, git, terminal rendering, and a CPU that other processes keep pinned.

This skill vs neighbors

How to reason

1. Observe: measure CPU per process before blaming anything. Quote the numbers.
2. Interpret: per-call cost × call rate × concurrent sessions. A 100 ms hook on every tool call across 3 agents matters; a 2 s Stop hook that runs once doesn't.
3. Classify: fix now (local, reversible) / ask (admin, committed, preference) / leave.
4. Verify: re-measure after each fix and report each change's effect separately.

Worked example

Observe: total CPU 100% with 3 sessions. Per-process sampling: ccusage ×5 at 49%, wmiprvse 8%, MsMpEng 3%. Interpret: the status line runs ccusage statusline every 10 s per session; each run re-reads ~10 GB of transcripts, and slow runs pile up. Classify: fix now. Remove the widget (back up the config first). Verify: no ccusage spawned in 2 min; total 53–72% → later ~30% as agent jobs finished (report the workload change separately from the fix).

Phase 0 — Measure (run exactly)

Windows (includes protected processes such as Defender):

$c = Get-Counter '\Process(*)\% Processor Time' -SampleInterval 5 -MaxSamples 1 -ErrorAction SilentlyContinue
$cores = (Get-CimInstance Win32_ComputerSystem).NumberOfLogicalProcessors
$c.CounterSamples | Where-Object { $_.InstanceName -notin '_total','idle' -and $_.Status -eq 0 } |
  Group-Object { $_.InstanceName -replace '#\d+$','' } |
  ForEach-Object { [pscustomobject]@{ Name=$_.Name; Count=$_.Count; Cpu=[math]::Round((($_.Group | Measure-Object CookedValue -Sum).Sum)/$cores,1) } } |
  Sort-Object Cpu -Descending | Select-Object -First 15

macOS / Linux: ps -eo pcpu,comm --sort=-pcpu | head -20 (macOS: ps -Ao pcpu,comm -r | head -20).

Take 3–4 samples over ~30 s. Avoid heavy Get-CimInstance Win32_Process loops while measuring; they inflate wmiprvse themselves.

Phase 1 — Status line

• A status line runs on every assistant message (debounced at 300 ms). statusLine.refreshInterval adds timed runs on top; leave it unset unless a widget needs a clock.
• Widgets that re-read transcripts on every render (ccusage statusline, transcript-parsing HUDs) scale with transcript volume × sessions. Prefer widgets that only read the JSON Claude Code passes on stdin (cost, context window, rate limits). Keep ccusage as an on-demand CLI.
• Cache slow git calls (ccstatusline: gitCacheTtlSeconds ≥ 30).
• Source: https://code.claude.com/docs/en/statusline

Phase 2 — Hooks

Inventory every hook in ~/.claude/settings.json and each repo's .claude/settings.json, then time each one (echo '{}' | <command>).

• Per-tool-call hooks (PreToolUse with matcher *, PostToolUse on Edit|Write) spawn a process per call. Narrow with matcher or the if field (permission-rule syntax) so non-matching calls never spawn.
• Per-edit lint/format that blocks for seconds duplicates lint-staged at commit and rewrites files under the agent (forcing re-reads). Remove it when pre-commit already runs eslint --fix.
• Synchronous Stop typecheck is invisible cost. For most events, including Stop, plain stdout goes to the debug log only, so the agent never sees the errors while every turn waits. Replace it with scripts/stop-typecheck.mjs registered with asyncRewake: true: background, skip-if-unchanged, wakes the agent only on a new error set. Copy it to <repo>/.claude/hooks/ and pass the repo's typecheck script name.
• Source: https://code.claude.com/docs/en/hooks (Exit code 0, async, asyncRewake, if)

Phase 3 — Instruction files and search scope

• AGENTS.md is skipped when any CLAUDE.md exists in the working directory or above it, which includes a parent folder holding all your repos. Load both with user settings "pluginConfigs": { "agents-md@builtin": { "options": { "instructionFiles": "claude-md-and-agents-md" } } } (ignored in project settings). Source: https://code.claude.com/docs/en/memory
• Keep each CLAUDE.md under ~200 lines; @imports load at launch and don't save context. Run /doctor prompt-audit to find bloat.
• Worktree folders inside the repo that are not gitignored (.worktrees/) make every Grep/Glob walk each copy and return duplicate hits. Add them to .git/info/exclude (local, no commit) or .gitignore. Check: git check-ignore -v .worktrees/x and compare rg --files | wc -l before and after.

Phase 4 — Effort and models

• Lower effort is faster and cheaper; Opus 5.5 defaults to medium. A global xhigh slows every routine turn. Suggest high (or the default) with /effort xhigh for hard tasks. On Opus 5.5, changing effort keeps the prompt cache.
• The built-in Explore agent inherits the main model. A user agent named Explore with model: haiku overrides it for fast, cheap searches.
• Fast mode (/fast): up to 2.5× faster output at a higher per-token price, billed from usage credits on subscriptions; enable at session start.
• These are preferences: recommend, then ask. Sources: https://code.claude.com/docs/en/model-config, https://code.claude.com/docs/en/sub-agents, https://code.claude.com/docs/en/fast-mode

Phase 5 — Worktree pile-up

Agents create worktrees faster than anyone removes them. Inventory with git worktree list --porcelain per repo and classify:

• KEEP: uncommitted changes, locked, path in a running process's command line, or activity in the last 24 h. Measure activity from HEAD and logs/HEAD mtimes in the worktree's git dir, not index: git status rewrites the index and makes every worktree look fresh.
• SAFE: clean, idle, and either merged into the default branch or its PR branch is [gone] on the remote (squash merges).
• REVIEW: clean, but holds commits not on the default branch.

Report the counts and list; remove SAFE ones only on approval, with git worktree remove (never --force).

Phase 6 — Operating system (Windows examples)

• Antivirus: prefer a Dev Drive with Defender performance mode over exclusions. Process exclusions (node.exe, git.exe) skip scanning of everything those processes write, so flag them as risk, not as a speed fix. Source: https://learn.microsoft.com/en-us/windows/dev-drive/
• Search indexer: exclude the repos folder via Settings → Privacy & security → Searching Windows → Add an excluded folder. The PreventIndexingCertainPaths policy key was observed to be ignored on Windows 11 Home; verify any exclusion with a probe file.
• Vendor utilities that query WMI on every process start (observed: Alienware Command Center's AWCC.SCSubAgent, ~8% CPU) scale with agent process churn. Attribute wmiprvse load by enabling the Microsoft-Windows-WMI-Activity/Trace channel for ~20 s (admin) and grouping ClientProcessId. Killing the sub-agent doesn't stick if a service respawns it; the fix is uninstalling the utility, which is the owner's call.
• Power plan on AC and Best performance; background terminals are throttled harder on battery.

Self-critique

Before reporting, fail the run if any of these are true:

• A cause was named without a per-process measurement behind it
• A fix was credited with a drop that a workload change explains
• A hook or setting was changed without timing it before and after
• A worktree, exclusion, or user preference was changed without approval
• An exclusion or policy was reported as working without a probe that proves it

Report

| # | Finding | Measured | Fix | Status (fixed / ask / leave) |

Then a before/after CPU table, the list of changed files with backups, and what's left for the owner (admin prompts, committed config, preferences).