# Execution Engineer: X4, firstmin vs main latency

## READ THIS FIRST
- **v1 (Execution Engineer, 7 Oct 12:30 Bangkok). Verdict: firstmin 178.128.20.136 is NOT slower than main 159.223.88.168 on any hop. Both sit in the same region (same Cloudflare edge, same dRPC edge, same 0.22 s to the sequencer). Moving the merged engine there is OK on latency.**
- **One hard condition before the move: firstmin has 1 CPU, 1 GB RAM and NO swap** (508 MB free). The w2 engine itself is small (64 MB, 0.7% CPU on main), but an out of memory kill would take the live engine down with no warning. Before the switch: add a 2 GB swapfile and set `OOMScoreAdjust=-900` on the engine unit (free), or resize firstmin to 2 GB (Ben, about $6 a month more). Keep backfills, scoreboard, halfc and health on main or research-box.

## Numbers (same script, same minute, both boxes; ms, median / p90)
| Hop | firstmin | main |
|---|---|---|
| Sequencer sendRaw, warm | 217 / 217 | 216 / 218 |
| Sequencer sendRaw, cold (new TLS) | 718 / 731 | 705 / 711 |
| Public RPC read, warm | 268 / 273 | 245 / 252 |
| Public sendRaw, warm | 270 / 293 | 246 / 247 |
| dRPC read, warm | 5 / 13 | 5 / 8 |
| dRPC read, cold | 72 / 75 | 65 / 74 |
| dRPC websocket head push age | 0.17 s / 0.56 s | 0.15 s / 0.55 s |
| TCP connect: sequencer / public / dRPC | 225 / 3 / 2 | 218 / 9 / 2 |
- Head age has an unknown clock offset (chrony not installed on either box), so read it as "same", not as an exact figure.
- Warm connections matter more than the box: cold to the sequencer is 0.7 s, warm 0.22 s. Idle test from firstmin: sequencer and public connections stay open after 10, 20, 30, 45, 60 and 90 s idle, so the Coder's 20 s keep-warm is enough (could even be 60 s).

## X5 (shadow fill grading): waiting
- Starts when the merged engine's mc5 shadow is running. Bars I will grade each shadow signal against the fm_mc5 live fill: same pool, gate within 30 s, entry fill within 2%, exit trigger within 1 s, exit fill within 5% (pool fee and our size counted). One table, one verdict.

Version: v1, 7 Oct 2026 12:30 Bangkok. Latest: http://159.223.88.168/hx-c9ois/sw/sw-exec-x4.md