diff --git a/benchmarking/compare/generate-report.js b/benchmarking/compare/generate-report.js
index a61f58909b..a06aaf9fc2 100644
--- a/benchmarking/compare/generate-report.js
+++ b/benchmarking/compare/generate-report.js
@@ -33,11 +33,38 @@ export function generate_report(outdir) {
 
 	write('');
 
-	for (let i = 0; i < results[0].length; i += 1) {
-		write(`${results[0][i].benchmark}`);
+	// match results by benchmark name — branches may have different benchmark
+	// lists (e.g. a benchmark that only exists on one of the branches), so
+	// pairing by array index would misattribute results
+	const by_name = results.map((result) => new Map(result.map((r) => [r.benchmark, r])));
+
+	/** @type {string[]} */
+	const names = [];
+
+	for (const result of results) {
+		for (const { benchmark } of result) {
+			if (!names.includes(benchmark)) {
+				names.push(benchmark);
+			}
+		}
+	}
+
+	for (const name of names) {
+		const entries = by_name.map((map) => map.get(name));
+		const missing = entries
+			.map((entry, b) => (entry === undefined ? branches[b] : null))
+			.filter((branch) => branch !== null);
+
+		write(`${name}`);
+
+		if (missing.length > 0) {
+			write(`  skipped (missing on ${missing.join(', ')})`);
+			write('');
+			continue;
+		}
 
 		for (const metric of ['time', 'gc_time']) {
-			const times = results.map((result) => +result[i][metric]);
+			const times = entries.map((entry) => +entry[metric]);
 			let min = Infinity;
 			let max = -Infinity;
 			let min_index = -1;
diff --git a/benchmarking/compare/runner.js b/benchmarking/compare/runner.js
index 31a8e6b44b..fa746f9869 100644
--- a/benchmarking/compare/runner.js
+++ b/benchmarking/compare/runner.js
@@ -1,18 +1,67 @@
+import { fork } from 'node:child_process';
+import { fileURLToPath } from 'node:url';
 import { reactivity_benchmarks } from '../benchmarks/reactivity/index.js';
 import { with_cpu_profile } from '../utils.js';
 
-const results = [];
-const PROFILE_DIR = process.env.BENCH_PROFILE_DIR;
+const PROFILE_DIR = process.env.BENCH_PROFILE_DIR ?? null;
+const single = process.env.BENCH_SINGLE;
 
-for (let i = 0; i < reactivity_benchmarks.length; i += 1) {
-	const benchmark = reactivity_benchmarks[i];
+if (single) {
+	// child mode — run a single benchmark and report the result to the parent
+	const benchmark = reactivity_benchmarks.find((b) => b.label === single);
 
-	process.stderr.write(`Running ${i + 1}/${reactivity_benchmarks.length} ${benchmark.label} `);
-	results.push({
-		benchmark: benchmark.label,
-		...(await with_cpu_profile(PROFILE_DIR, benchmark.label, () => benchmark.fn()))
-	});
-	process.stderr.write('\x1b[2K\r');
-}
+	if (!benchmark) {
+		throw new Error(`Unknown benchmark ${single}`);
+	}
+
+	const result = await with_cpu_profile(PROFILE_DIR, benchmark.label, () => benchmark.fn());
+
+	// exit via the callback so the message is guaranteed to be delivered
+	/** @type {NodeJS.Process} */ (process).send(result, () => process.exit(0));
+} else {
+	// parent mode — run every benchmark in its own child process, so that
+	// heap/GC/JIT state from one benchmark cannot contaminate the others
+	const filename = fileURLToPath(import.meta.url);
+	const results = [];
+
+	for (let i = 0; i < reactivity_benchmarks.length; i += 1) {
+		const benchmark = reactivity_benchmarks[i];
+
+		process.stderr.write(`Running ${i + 1}/${reactivity_benchmarks.length} ${benchmark.label} `);
+
+		const result = await new Promise((fulfil, reject) => {
+			const child = fork(filename, [], {
+				env: {
+					...process.env,
+					BENCH_SINGLE: benchmark.label
+				}
+			});
+
+			/** @type {object | null} */
+			let message_received = null;
 
-process.send(results);
+			child.on('message', (message) => {
+				message_received = /** @type {object} */ (message);
+			});
+
+			child.on('error', reject);
+
+			child.on('exit', (code) => {
+				if (message_received === null) {
+					reject(new Error(`benchmark ${benchmark.label} exited with code ${code}`));
+				} else {
+					fulfil(message_received);
+				}
+			});
+		});
+
+		results.push({
+			benchmark: benchmark.label,
+			.../** @type {object} */ (result)
+		});
+
+		process.stderr.write('\x1b[2K\r');
+	}
+
+	/** @type {NodeJS.Process} */ (process).send(results);
+}
diff --git a/benchmarking/run.js b/benchmarking/run.js
index 80e40a5ff1..e44e816dd0 100644
--- a/benchmarking/run.js
+++ b/benchmarking/run.js
@@ -1,94 +1,149 @@
+import { fork } from 'node:child_process';
+import { fileURLToPath } from 'node:url';
 import * as $ from '../packages/svelte/src/internal/client/index.js';
 import { reactivity_benchmarks } from './benchmarks/reactivity/index.js';
 import { ssr_benchmarks } from './benchmarks/ssr/index.js';
 import { with_cpu_profile } from './utils.js';
 
-// e.g. `pnpm bench kairo` to only run the kairo benchmarks
-const filters = process.argv.slice(2);
-
 const PROFILE_DIR = './benchmarking/.profiles';
 
-const suites = [
-	{
-		benchmarks: reactivity_benchmarks.filter(
-			(b) => filters.length === 0 || filters.some((f) => b.label.includes(f))
-		),
-		name: 'reactivity benchmarks'
-	},
-	{
-		benchmarks: ssr_benchmarks.filter(
-			(b) => filters.length === 0 || filters.some((f) => b.label.includes(f))
-		),
-		name: 'server-side rendering benchmarks'
-	}
-].filter((suite) => suite.benchmarks.length > 0);
-
-if (suites.length === 0) {
-	console.log('No benchmarks matched provided filters');
-	process.exit(1);
-}
-
-const COLUMN_WIDTHS = [25, 9, 9];
-const TOTAL_WIDTH = COLUMN_WIDTHS.reduce((a, b) => a + b);
-
-const pad_right = (str, n) => str + ' '.repeat(n - str.length);
-const pad_left = (str, n) => ' '.repeat(n - str.length) + str;
+const single = process.env.BENCH_SINGLE;
 
-let total_time = 0;
-let total_gc_time = 0;
+if (single) {
+	// child mode — run a single benchmark and report the result to the parent
+	const benchmark = [...reactivity_benchmarks, ...ssr_benchmarks].find((b) => b.label === single);
 
-$.push({}, true);
+	if (!benchmark) {
+		throw new Error(`Unknown benchmark ${single}`);
+	}
 
-try {
-	for (const { benchmarks, name } of suites) {
-		let suite_time = 0;
-		let suite_gc_time = 0;
+	$.push({}, true);
+
+	const result = await with_cpu_profile(PROFILE_DIR, benchmark.label, () => benchmark.fn());
+
+	$.pop();
+
+	// exit via the callback so the message is guaranteed to be delivered
+	/** @type {NodeJS.Process} */ (process).send(result, () => process.exit(0));
+} else {
+	// parent mode — run every benchmark in its own child process, so that
+	// heap/GC/JIT state from one benchmark cannot contaminate the others
+
+	// e.g. `pnpm bench kairo` to only run the kairo benchmarks
+	const filters = process.argv.slice(2);
+
+	const suites = [
+		{
+			benchmarks: reactivity_benchmarks.filter(
+				(b) => filters.length === 0 || filters.some((f) => b.label.includes(f))
+			),
+			name: 'reactivity benchmarks'
+		},
+		{
+			benchmarks: ssr_benchmarks.filter(
+				(b) => filters.length === 0 || filters.some((f) => b.label.includes(f))
+			),
+			name: 'server-side rendering benchmarks'
+		}
+	].filter((suite) => suite.benchmarks.length > 0);
 
-		console.log(`\nRunning ${name}...\n`);
-		console.log(
-			pad_right('Benchmark', COLUMN_WIDTHS[0]) +
-				pad_left('Time', COLUMN_WIDTHS[1]) +
-				pad_left('GC time', COLUMN_WIDTHS[2])
-		);
-		console.log('='.repeat(TOTAL_WIDTH));
+	if (suites.length === 0) {
+		console.log('No benchmarks matched provided filters');
+		process.exit(1);
+	}
 
-		for (const benchmark of benchmarks) {
-			const results = await with_cpu_profile(PROFILE_DIR, benchmark.label, () => benchmark.fn());
+	const filename = fileURLToPath(import.meta.url);
+
+	/**
+	 * @param {string} label
+	 * @returns {Promise<{ time: number, gc_time: number }>}
+	 */
+	const run_benchmark = (label) => {
+		return new Promise((fulfil, reject) => {
+			const child = fork(filename, [], {
+				env: {
+					...process.env,
+					BENCH_SINGLE: label
+				}
+			});
+
+			/** @type {{ time: number, gc_time: number } | null} */
+			let result = null;
+
+			child.on('message', (message) => {
+				result = /** @type {{ time: number, gc_time: number }} */ (message);
+			});
+
+			child.on('error', reject);
+
+			child.on('exit', (code) => {
+				if (result === null) {
+					reject(new Error(`benchmark ${label} exited with code ${code}`));
+				} else {
+					fulfil(result);
+				}
+			});
+		});
+	};
+
+	const COLUMN_WIDTHS = [25, 9, 9];
+	const TOTAL_WIDTH = COLUMN_WIDTHS.reduce((a, b) => a + b);
+
+	/** @type {(str: string, n: number) => string} */
+	const pad_right = (str, n) => str + ' '.repeat(n - str.length);
+	/** @type {(str: string, n: number) => string} */
+	const pad_left = (str, n) => ' '.repeat(n - str.length) + str;
+
+	let total_time = 0;
+	let total_gc_time = 0;
+
+	try {
+		for (const { benchmarks, name } of suites) {
+			let suite_time = 0;
+			let suite_gc_time = 0;
+
+			console.log(`\nRunning ${name}...\n`);
+			console.log(
+				pad_right('Benchmark', COLUMN_WIDTHS[0]) +
+					pad_left('Time', COLUMN_WIDTHS[1]) +
+					pad_left('GC time', COLUMN_WIDTHS[2])
+			);
+			console.log('='.repeat(TOTAL_WIDTH));
+
+			for (const benchmark of benchmarks) {
+				const results = await run_benchmark(benchmark.label);
+				console.log(
+					pad_right(benchmark.label, COLUMN_WIDTHS[0]) +
+						pad_left(results.time.toFixed(2), COLUMN_WIDTHS[1]) +
+						pad_left(results.gc_time.toFixed(2), COLUMN_WIDTHS[2])
+				);
+				total_time += results.time;
+				total_gc_time += results.gc_time;
+				suite_time += results.time;
+				suite_gc_time += results.gc_time;
+			}
+
+			console.log('='.repeat(TOTAL_WIDTH));
 			console.log(
-				pad_right(benchmark.label, COLUMN_WIDTHS[0]) +
-					pad_left(results.time.toFixed(2), COLUMN_WIDTHS[1]) +
-					pad_left(results.gc_time.toFixed(2), COLUMN_WIDTHS[2])
+				pad_right('suite', COLUMN_WIDTHS[0]) +
+					pad_left(suite_time.toFixed(2), COLUMN_WIDTHS[1]) +
+					pad_left(suite_gc_time.toFixed(2), COLUMN_WIDTHS[2])
 			);
-			total_time += results.time;
-			total_gc_time += results.gc_time;
-			suite_time += results.time;
-			suite_gc_time += results.gc_time;
+			console.log('='.repeat(TOTAL_WIDTH));
 		}
 
-		console.log('='.repeat(TOTAL_WIDTH));
-		console.log(
-			pad_right('suite', COLUMN_WIDTHS[0]) +
-				pad_left(suite_time.toFixed(2), COLUMN_WIDTHS[1]) +
-				pad_left(suite_gc_time.toFixed(2), COLUMN_WIDTHS[2])
-		);
-		console.log('='.repeat(TOTAL_WIDTH));
-	}
-
-	if (PROFILE_DIR !== null) {
 		console.log(`\nCPU profiles written to ${PROFILE_DIR}`);
+	} catch (e) {
+		// eslint-disable-next-line no-console
+		console.error(e);
+		process.exit(1);
 	}
-} catch (e) {
-	// eslint-disable-next-line no-console
-	console.error(e);
-	process.exit(1);
-}
 
-$.pop();
+	console.log('');
 
-console.log('');
-
-console.log(
-	pad_right('total', COLUMN_WIDTHS[0]) +
-		pad_left(total_time.toFixed(2), COLUMN_WIDTHS[1]) +
-		pad_left(total_gc_time.toFixed(2), COLUMN_WIDTHS[2])
-);
+	console.log(
+		pad_right('total', COLUMN_WIDTHS[0]) +
+			pad_left(total_time.toFixed(2), COLUMN_WIDTHS[1]) +
+			pad_left(total_gc_time.toFixed(2), COLUMN_WIDTHS[2])
+	);
+}