Files
homarr/docs/perf/README.md
T
Thomas Camlong 083a926719 docs(perf): give every one of the 50 widgets a verdict
Completes the sweep: 11 fixed, 8 triaged, 10 read and found clean, 21 verified
bounded. Each verdict records the evidence behind it, because "I read this" and
"its list cannot get long" are different strengths of claim and should not look
alike in a table.

The four widgets the ranking flagged as most likely to hide something all came
back clean, and three were already bounded before I looked - traefik slices to
what its width shows, umami to its own limit option, beszel-alerts to
options.maxHistoryItems. system-resources looked worst of all with 14 unmemoised
maps, until it turned out none of the six chart components it feeds is memoised
either, so a stable array identity would preserve nothing.
2026-08-11 16:33:33 +02:00

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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.