Reduce Preact prop updater allocations

[JoviDeCroock]

Each signal-bound DOM property currently allocates a wrapper object, updater closure, effect callback closure, and bound disposer. Make the Effect itself the property updater and share its callback and update methods across bindings, while retaining the wrapper Signal that preserves rebinding semantics.

Trade-off: signals.mjs grows from 1732 B to 1821 B gzip (+89 B). Each live binding is 72 B smaller, so the shipped cost breaks even after a few bound properties.

Signal-bound DOM properties — 52.5% faster creation, 72 B smaller, 11.1% faster updates

import { h, render } from "preact";
import { signal } from "@preact/signals";

const count = 10_000;
const values = Array.from({ length: count }, (_, i) => signal(`before-${i}`));
const root = document.createElement("div");
document.body.append(root);

function App() {
  return h(
    "main",
    null,
    values.map((value, i) => h("span", { title: value }, i))
  );
}
render(h(App), root);

async function write(value) {
  const start = performance.now();
  for (let i = 0; i < count; i++) values[i].value = `${value}-${i}`;
  await Promise.resolve();
  await Promise.resolve();
  await Promise.resolve();
  return performance.now() - start;
}

for (let i = 0; i < 5; i++) await write(`warm-${i}`);
const samples = [];
for (let i = 0; i < 15; i++) samples.push(await write(`sample-${i}`));
console.log(Math.min(...samples));

[changeset-bot]

🦋 Changeset detected

Latest commit: eef7237

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@preact/signals	Patch
preact-signals-devtools	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

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[github-actions]

Size Change: -6.94 kB (-3.35%)

Total Size: 200 kB

📦 View Changed

Filename	Size	Change
docs/dist/assets/bench-********.js	1.6 kB	+2 B (+0.13%)
docs/dist/assets/devtools-********.js	915 B	+4 B (+0.44%)
docs/dist/assets/EmbeddedDevtools-********.js	23.1 kB	+73 B (+0.32%)
docs/dist/assets/index-********.js	1.09 kB	-7.42 kB (-87.15%)	🏆
docs/dist/assets/signals.module-********.js	2.74 kB	+80 B (+3.01%)
docs/dist/assets/Unmount-********.js	652 B	+1 B (+0.15%)
docs/dist/assets/utils.module-********.js	521 B	+1 B (+0.19%)
docs/dist/basic-********.js	248 B	+1 B (+0.4%)
packages/devtools-ui/dist/devtools-ui.js	21.3 kB	+67 B (+0.32%)
packages/devtools-ui/dist/devtools-ui.mjs	20.7 kB	+74 B (+0.36%)
packages/preact/dist/signals.js	1.91 kB	+84 B (+4.61%)	🔍
packages/preact/dist/signals.mjs	1.85 kB	+88 B (+5%)	🔍

ℹ️ View Unchanged

Filename	Size
docs/dist/assets/client-********.js	46.6 kB
docs/dist/assets/jsxRuntime.module-********.js	300 B
docs/dist/assets/preact.module-********.js	4.74 kB
docs/dist/assets/signals-core.module-********.js	1.92 kB
docs/dist/assets/style-********.css	7.19 kB
docs/dist/nesting-********.js	1.15 kB
docs/dist/react-********.js	242 B
packages/core/dist/signals-core.js	1.94 kB
packages/core/dist/signals-core.mjs	1.93 kB
packages/debug/dist/debug.js	4.72 kB
packages/debug/dist/debug.mjs	4.24 kB
packages/devtools-adapter/dist/devtools-adapter.js	2.36 kB
packages/devtools-adapter/dist/devtools-adapter.mjs	2.07 kB
packages/preact-transform/dist/signals-transform.js	1.66 kB
packages/preact-transform/dist/signals-transform.mjs	1.61 kB
packages/preact-transform/dist/signals-transform.umd.js	1.77 kB
packages/react-transform/dist/signals-transform.js	7.63 kB
packages/react-transform/dist/signals-transform.mjs	6.78 kB
packages/react-transform/dist/signals-transform.umd.js	7.75 kB
packages/react/dist/signals.js	214 B
packages/react/dist/signals.mjs	165 B
packages/vite-plugin/dist/vite-plugin.js	8.86 kB
packages/vite-plugin/dist/vite-plugin.mjs	7.86 kB

_{compressed-size-action}

[JoviDeCroock]

Byte size impact is a bit too large