# Performance pass — 10+ concurrent users, lean local mode

Audit 2026-10-07 against a copy of the real DB (1.2 GB, 253K events). Baseline,
10 simulated browsers + 10 hooks/s for 90 s: event-loop delay p99 1239 ms, request
p95 ~10 s, 266 failed. Bench tools: `/tmp/ahperf/tools/` (`clients.js`, `hookload.js`,
`bench.js`). Target: ELD p99 < 100 ms, request p95 < 300 ms, 0 failed.

Dev (4830) and prod (4820) keep sharing one `dashboard.db`.

## Server
- [x] S1 `/api/workflows/skill-usage`: `+event_type` + range instead of LIKE (784 ms → ~5 ms)
- [x] S2 `/api/analytics` into `read-pool.js` JOBS + short memo keyed by scope/args
- [x] S3 `/api/workflows` result memo (30 s)
- [x] S4 `idx_events_session_type_tool` replaces `idx_events_session_type` (partial index skipped: the 30 s workflows memo covers it); `cache_size`/`mmap_size`
- [x] S5 WAL: `wal_autocheckpoint=0` on the main connection, PASSIVE checkpoint off-thread, fallback
- [x] S6 tmux: 1 s `list-sessions` memo (cleared by this process's new/kill), one `liveSessions()` per `GET /api/lanes`, attach options chained (4 spawns → 2), async `ps` for the watchdog, heal tick skipped when nothing runs
- [x] S7 hooks: hoist TurnDuration/APIError statements + watermark; one `listLanes()` per hook; hourly upsert only on change
- [x] S8 hooks.js `session_id` rebind skipped for slot 1–9 panes
- [x] S9 startup subagent backfill: do not re-parse unstampable files every boot
- [x] S10 pty-attach backpressure
- [x] S11 serve pre-compressed `.br`/`.gz` assets
- [x] S12 broadcasts only after the hook transaction commits
- [x] S13 `new_event` carries `id`
- [~] S14 codex-usage memo — DROPPED: an in-memory "already read" map survives Clear data and blocks the re-import (caught by codex-usage tests); the pass costs ~5 ms per 15 s
- [x] S15 transcript newline scan via `indexOf`

## Client
- [x] C1 no WS-triggered refetch in hidden tabs; hidden-tab pollers paused; drop hourly `/updates/check`
- [x] C2 throttle WorkspaceTree / WorkspaceSessionList / `/api/run` refetchers; lazy notification lookup
- [x] C3 WS reconnect jitter; terminal retry backoff
- [x] C4 heavier throttles for aggregates / detail refetches; Monitor `keepIfSame`; GET in-flight dedupe
- [x] C5 build: pre-compress assets, `sourcemap: "hidden"`
- [x] C6 load only the active locale; lazy routes/Sagi/modals/xterm
- [x] C7 Sagi re-render fixes; service-worker asset cache

## Verify
- [x] `npm run test:server` (2556/2556), `npm run test:client` (1084/1084), `tsc -b`, header check; headless Chrome smoke (en + vi, 4 pages, terminal attach)
- [x] re-run the 10-client bench (server side, same old-client simulation) — see Result

## Result (server, `clients.js 10 90 10`, same simulated old client)

| | before | after |
|---|---|---|
| event-loop delay p99 / max | 1239 ms / 2.0 s | 31.8 ms / 94 ms |
| failed requests | 266 | 0 |
| requests served | 74/s | 111/s |
| hook p95 / p99 (10/s) | — | 7.6 / 28.8 ms |
| RSS | 633 MB | 346 MB |

Biggest single cause after the first round: 2,247 synchronous `tmux list-sessions`
from `GET /api/run` = 60 s of a 90 s run blocked (fork of a 600 MB process); the 1 s
memo removed it. The client fixes (C1–C4) cut the request rate itself on top.