Thomas Camlong
09df2910c5
Sourced with the skills CLI - npx skills find "react performance", then
npx skills use affaan-m/ecc@react-performance, an adaptation of vercel-labs
react-best-practices: 70+ rules across 8 categories. Every mechanically
checkable rule was run against the widgets.
Seven already hold, and that is worth recording as much as a finding: no widget
registers a scroll listener, no numeric && can render a literal 0, the nested
array scans that exist are over single-digit collections, React.cache() is
applied, TanStack Query does the deduplication, content-visibility is on the six
lists that need it, and the two components-declared-in-render were already found
and fixed.
One rule this codebase deliberately contradicts: the skill prefers React 19
<Activity> over unmounting for tabs, and this pass did the opposite with
keepMounted={false}. The rule optimises for switching; a dashboard optimises for
mounting. Every board load mounts every widget while a user switches a widget's
inner tabs rarely, so building a hidden monitoring view on every page load buys
a faster switch nobody performs. Where state loss would show - custom-api's user
JSX, the edit modal's forms - the panels stay mounted.
Two candidates declined rather than guessed at, both recorded with reasoning:
the 20+ `data = []` defaults only destabilise while data is undefined, since
react-query returns a stable reference once loaded; and the 7 unlisted Mantine
entry points need two production builds and a first-load-JS diff before anyone
claims they help. @homarr/ui is not eligible at all despite 111 importers,
because Next's barrel optimiser only rewrites pure re-export files.
Also records the process error behind the earlier "no skills CLI" claim: the
entries in ~/.claude/skills are symlinks, which find -type f skips, so the
directory looked empty right after cat had succeeded on a file inside it.
Homarr performance investigation
Measured work on Homarr's memory and rendering cost, split by subject. Every figure here comes from
a run of scripts/benchmarks/stress-restore.mts against a restored real backup — 4 boards, 51
widgets, 11 integrations, driven through an actual login — not from a synthetic or empty container.
| document | subject |
|---|---|
| SERVER-MEMORY.md | What the container's RAM is made of, and the changes that reduced it |
| CLIENT-PERFORMANCE.md | Dashboard rendering cost in Chrome: DOM, fibers, images, paint |
| WIDGET-AUDIT.md | All 50 widgets, one at a time, with a verdict and the evidence for each |
| REJECTED.md | Ideas that were implemented and measured, then abandoned — with the numbers |
| METHODOLOGY.md | The tools, and the measurement traps that produced wrong answers |
| NEXT-STEPS.md | Handoff: what is unverified, what to do next, and the set for a clean PR |
Headline result
Server RAM, merge-base 06724cfeb vs this branch, two alternated runs per side, reported as cgroup
anonymous memory because that is what counts against a container limit and cannot be reclaimed:
| stage | before | after | change |
|---|---|---|---|
| peak | 376.6 MiB | 279.3 MiB | −26% |
| boot idle | 130.5 MiB | 62.4 MiB | −52% |
| after sign-in | 247.4 MiB | 142.9 MiB | −42% |
| dashboard loaded | 293.4 MiB | 170.4 MiB | −42% |
| 4 tabs, 2 boards | 366.5 MiB | 258.2 MiB | −30% |
| after 2 min idle soak | 323.7 MiB | 200.8 MiB | −38% |
No before/after range overlaps at any stage. The cost is +18% CPU (solid, non-overlapping).
The changes that did it, by ratio
| change | size | effect |
|---|---|---|
--max-semi-space-size=4 |
1 line | −19% idle, −21% peak |
preloadEntriesOnStart: false |
1 line | −52% anon at idle, 310 fewer files even at full load |
| Umami: stop fetching 100k raw events per refresh | 1 file | −26% peak, −93% transient buffers |
serverExternalPackages (mysql2/pg + 8 more) |
1 block | −21 MiB idle |
| ssh2's 16 MiB WASM heap (docker-modem patch) | 1 patch | −15 to −18 MiB external |
content-visibility on media-release cards |
4 lines | −59% image requests, −41% layout objects |
What is left, and why it is hard
One lever has real headroom and it pays twice. Roughly 41 MiB of retained bundle source and ~38 MiB of V8 compiler zone memory both scale with how much JavaScript the server loads and compiles, and the largest single contributor is a 16.10 MiB subtree reached by every API route — the tRPC router importing every integration eagerly. Reducing that reduces both.
Everything else has been measured and closed: see REJECTED.md.