Optimize dependency value change checks by allowing earlier exists from the loop

[jviide]

This pull request modifies the dependency version change check used by computed & effect. Before the change each dependency's ._refresh() was called before checking the dependency's version number. After this change the version number is checked first, then ._refresh() is called, and then the version number is checked again. In practice this allows the dependency checks break the loop earlier, avoiding calls to _refresh() for a) plain signals that have changed and b) computed values that get repeated reads.

The following benchmark demonstrates the impact in a scenario that contains both a) and b):

import * as core from "@preact/signals-core";

const count = core.signal(0);
const double = core.computed(() => count.value * 2);
core.effect(() => double.value + count.value);
core.effect(() => double.value + count.value);
core.effect(() => double.value + count.value);

console.time("core");

for (let i = 0; i < 20000000; i++) {
count.value++;
double.value;
}

console.timeEnd("core");

The results before the change:

core: 2.616s

And after the change:

core: 2.196s

[changeset-bot]

🦋 Changeset detected

Latest commit: 49756ae

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

This PR includes changesets to release 1 package

Name	Type
@preact/signals-core	Patch

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[github-actions]

Size Change: +284 B (0%)

Total Size: 67.5 kB

Filename	Size	Change
docs/dist/assets/index.********.js	1.08 kB	+245 B (+29%)	🚨
docs/dist/assets/signals-core.module.********.js	1.36 kB	+11 B (+1%)
docs/dist/assets/signals.module.********.js	1.97 kB	+2 B (0%)
docs/dist/demos-********.js	3.35 kB	+3 B (0%)
docs/dist/react-********.js	240 B	+1 B (0%)
packages/core/dist/signals-core.js	1.42 kB	+11 B (+1%)
packages/core/dist/signals-core.mjs	1.44 kB	+11 B (+1%)

ℹ️ View Unchanged

Filename	Size
docs/dist/assets/client.********.js	45.8 kB
docs/dist/assets/jsxRuntime.module.********.js	282 B
docs/dist/assets/preact.module.********.js	4 kB
docs/dist/assets/style.********.js	21 B
docs/dist/assets/style.********.css	1.21 kB
docs/dist/basic-********.js	243 B
docs/dist/nesting-********.js	1.13 kB
packages/preact/dist/signals.js	1.19 kB
packages/preact/dist/signals.mjs	1.15 kB
packages/react/dist/signals.js	833 B
packages/react/dist/signals.mjs	810 B

_{compressed-size-action}

[marvinhagemeister]

🎉