Next loads the module graph for all 74 app routes when the server starts. Measured
here: 1,114 files and 24 MiB of source resident before the first request, including
one shared 16 MiB subtree behind the API routes that reaches every integration
client. A dashboard serves a handful of routes per session.
`experimental.preloadEntriesOnStart: false` is Next's documented switch for this.
An earlier round of this work recorded route preloading as "framework behaviour, not
something this codebase sets" - that was wrong, and the findings doc is corrected.
Deterministic per-stage measurements, identical across both runs on each side:
stage source loaded files heapUsed
boot idle 24.0 -> 10.6 MiB 1114 -> 706 70.7 -> 44.8 (-37%)
post-login 27.9 -> 19.3 MiB 1215 -> 884 123.8 -> 109.8
board loaded 29.0 -> 21.7 MiB 1323 -> 1006 (run-to-run noise)
multi-tab 29.2 -> 22.9 MiB 1325 -> 1015 139.7 -> 127.8
post-soak 29.2 -> 22.9 MiB 1325 -> 1015 142.5 -> 127.4
The important part is the last two rows: 310 files and 6.3 MiB of source stay
unloaded even after a full multi-tab session, so this is not merely deferred cost -
routes the session never visits are never paid for at all. Live heap is lower at
every stage, by 26 MiB at idle and 12-15 MiB under load and at rest.
Peak node RSS does not move (350.3 -> 346.1, spreads overlap). V8 sizes its heap
against available headroom, so a smaller live set does not shrink peak RSS; what
improves is idle footprint and how much room is left before the heap cap. Median
board load is +3% with overlapping spreads, so the first-hit cost this trades for
did not show at this workload.
Full E2E suite passes 8/8 against the built image.
Thomas Camlong
bcea4733b9