An add-on's storage.get read and parsed its whole store file on every call,
and storage.set read, parsed and rewrote it — synchronously, on the main
thread. Traced on a real profile (installed 0.3.70): with a 7.5 MB Aegis
store, 30 of the first 35 s of main-thread time went to storage.get, the
window sat in "Not Responding" from 3 s to 19 s, and the first page showed at
19 s. One get cost ~73 ms; Aegis does dozens per state update.
lib/addon-store.cjs keeps one in-memory copy per store, shared by the
add-on's api.storage (addons-host.js) and its pages (addon-storage-* IPC in
main.js). After a one-time load a get costs microseconds; values are copied
in and out (structuredClone), so callers keep the old semantics. Writes are
coalesced (100 ms) and land as temp-file + rename, and are flushed on quit;
a store that doesn't parse is moved aside instead of being replaced by {}.
Measured on copies of the same profile, dev build:
first page 16.9-17.6 s -> 1.5-1.7 s; main thread blocked 24.7-25.8 s of
30 -> 1.0-1.1 s; longest freeze 13.7-15.0 s -> 0.6 s.
The Aegis side (capping its unbounded txCache) ships separately through
Aegis's own update channel. The boot tracer gains total/longest block columns.
With a script as the Electron entry, the app path is the script's folder;
main.js loads chrome.html, home.html and every overlay by relative name, so
all of them failed with ERR_FILE_NOT_FOUND and every traced run measured a
broken launch (it also left a window showing the error page). The tracer now
sets app.setAppPath to TheseusNavigator, records failed main-frame loads, and
run.mjs marks such a run INVALID.
Re-measured (warm runs, fresh profile): the per-overlay lazy loading in
e524c12 saves 5 processes and ~100 MB private memory at 15 s — not ~30 MB
with an unchanged process count as its message says; that figure came from
the broken runs. The BNS indexer utilityProcess costs ~60-75 MB.
Measures dev-tree launches against a throwaway profile, without changing
main.js: time to app ready, toolbar and first page; main-thread blocks; add-on
activation; overlay pages loaded; main-process fetches; process count and
private memory at 15 s. One row per run, so a startup change can be compared
with the numbers before it.
node scripts/boot-trace/run.mjs [--runs 3] [--seconds 25] [--fresh] [--profile <dir>]
