diff --git a/package.json b/package.json
index 8ed7e30cc2..1a617286f7 100644
--- a/package.json
+++ b/package.json
@@ -69,6 +69,7 @@
 		"ava": "^6.0.1",
 		"c8": "^9.1.0",
 		"get-node": "^15.0.0",
+		"is-in-ci": "^0.1.0",
 		"is-running": "^2.1.0",
 		"path-exists": "^5.0.0",
 		"path-key": "^4.0.0",
diff --git a/test/helpers/parallel.js b/test/helpers/parallel.js
new file mode 100644
index 0000000000..3f96acafc3
--- /dev/null
+++ b/test/helpers/parallel.js
@@ -0,0 +1,3 @@
+import isInCi from 'is-in-ci';
+
+export const PARALLEL_COUNT = isInCi ? 10 : 100;
diff --git a/test/io/output-async.js b/test/io/output-async.js
index 8ab44a555f..081948418b 100644
--- a/test/io/output-async.js
+++ b/test/io/output-async.js
@@ -7,6 +7,7 @@ import {STANDARD_STREAMS} from '../helpers/stdio.js';
 import {foobarString} from '../helpers/input.js';
 import {setFixtureDirectory} from '../helpers/fixtures-directory.js';
 import {assertMaxListeners} from '../helpers/listeners.js';
+import {PARALLEL_COUNT} from '../helpers/parallel.js';
 
 setFixtureDirectory();
 
@@ -39,11 +40,9 @@ const testListenersCleanup = async (t, isMultiple) => {
 test.serial('process.std* listeners are cleaned up on success with a single input', testListenersCleanup, false);
 test.serial('process.std* listeners are cleaned up on success with multiple inputs', testListenersCleanup, true);
 
-const subprocessesCount = 100;
-
 test.serial('Can spawn many subprocesses in parallel', async t => {
 	const results = await Promise.all(
-		Array.from({length: subprocessesCount}, () => execa('noop.js', [foobarString])),
+		Array.from({length: PARALLEL_COUNT}, () => execa('noop.js', [foobarString])),
 	);
 	t.true(results.every(({stdout}) => stdout === foobarString));
 });
@@ -57,7 +56,7 @@ const testMaxListeners = async (t, isMultiple, maxListenersCount) => {
 
 	try {
 		const results = await Promise.all(
-			Array.from({length: subprocessesCount}, () => execa('empty.js', getComplexStdio(isMultiple))),
+			Array.from({length: PARALLEL_COUNT}, () => execa('empty.js', getComplexStdio(isMultiple))),
 		);
 		t.true(results.every(({exitCode}) => exitCode === 0));
 	} finally {
diff --git a/test/ipc/buffer-messages.js b/test/ipc/buffer-messages.js
index 730220d00e..a14d3d2abf 100644
--- a/test/ipc/buffer-messages.js
+++ b/test/ipc/buffer-messages.js
@@ -2,6 +2,7 @@ import test from 'ava';
 import {execa, execaSync} from '../../index.js';
 import {setFixtureDirectory} from '../helpers/fixtures-directory.js';
 import {foobarString, foobarArray} from '../helpers/input.js';
+import {PARALLEL_COUNT} from '../helpers/parallel.js';
 
 setFixtureDirectory();
 
@@ -57,11 +58,9 @@ test('Sets empty error.ipcOutput, sync', t => {
 	t.deepEqual(ipcOutput, []);
 });
 
-const HIGH_CONCURRENCY_COUNT = 10;
-
 test.serial('Can retrieve initial IPC messages under heavy load', async t => {
 	await Promise.all(
-		Array.from({length: HIGH_CONCURRENCY_COUNT}, async (_, index) => {
+		Array.from({length: PARALLEL_COUNT}, async (_, index) => {
 			const {ipcOutput} = await execa('ipc-send-argv.js', [`${index}`], {ipc: true});
 			t.deepEqual(ipcOutput, [`${index}`]);
 		}),
diff --git a/test/ipc/get-each.js b/test/ipc/get-each.js
index b8284b9381..394c3e6cac 100644
--- a/test/ipc/get-each.js
+++ b/test/ipc/get-each.js
@@ -3,6 +3,7 @@ import {execa} from '../../index.js';
 import {setFixtureDirectory} from '../helpers/fixtures-directory.js';
 import {foobarString, foobarArray} from '../helpers/input.js';
 import {iterateAllMessages} from '../helpers/ipc.js';
+import {PARALLEL_COUNT} from '../helpers/parallel.js';
 
 setFixtureDirectory();
 
@@ -82,15 +83,13 @@ test('Exceptions in subprocess.getEachMessage() disconnect', async t => {
 	t.deepEqual(ipcOutput, [foobarString]);
 });
 
-const HIGH_CONCURRENCY_COUNT = 10;
-
 test.serial('Can send many messages at once with exports.getEachMessage()', async t => {
 	const subprocess = execa('ipc-iterate.js', {ipc: true});
-	await Promise.all(Array.from({length: HIGH_CONCURRENCY_COUNT}, (_, index) => subprocess.sendMessage(index)));
+	await Promise.all(Array.from({length: PARALLEL_COUNT}, (_, index) => subprocess.sendMessage(index)));
 	await subprocess.sendMessage(foobarString);
 
 	const {ipcOutput} = await subprocess;
-	t.deepEqual(ipcOutput, Array.from({length: HIGH_CONCURRENCY_COUNT}, (_, index) => index));
+	t.deepEqual(ipcOutput, Array.from({length: PARALLEL_COUNT}, (_, index) => index));
 });
 
 test('Disconnecting in the current process stops exports.getEachMessage()', async t => {
diff --git a/test/ipc/get-one.js b/test/ipc/get-one.js
index 2e2c30e178..97c2abc0b7 100644
--- a/test/ipc/get-one.js
+++ b/test/ipc/get-one.js
@@ -10,6 +10,7 @@ import {
 	subprocessExchange,
 	alwaysPass,
 } from '../helpers/ipc.js';
+import {PARALLEL_COUNT} from '../helpers/parallel.js';
 
 setFixtureDirectory();
 
@@ -80,11 +81,9 @@ const testFilterSubprocess = async (t, fixtureName, expectedOutput) => {
 test('exports.getOneMessage() can filter messages', testFilterSubprocess, 'ipc-echo-filter.js', [foobarArray[1]]);
 test('exports.exchangeMessage() can filter messages', testFilterSubprocess, 'ipc-echo-filter-exchange.js', ['.', foobarArray[1]]);
 
-const HIGH_CONCURRENCY_COUNT = 10;
-
 const testHeavyLoad = async (t, exchangeMethod) => {
 	await Promise.all(
-		Array.from({length: HIGH_CONCURRENCY_COUNT}, async (_, index) => {
+		Array.from({length: PARALLEL_COUNT}, async (_, index) => {
 			const subprocess = execa('ipc-send-argv.js', [`${index}`], {ipc: true, buffer: false});
 			t.is(await exchangeMethod(subprocess, {}), `${index}`);
 			await subprocess;
diff --git a/test/ipc/send.js b/test/ipc/send.js
index 981ac293e5..89af8f685b 100644
--- a/test/ipc/send.js
+++ b/test/ipc/send.js
@@ -3,6 +3,7 @@ import {execa} from '../../index.js';
 import {setFixtureDirectory} from '../helpers/fixtures-directory.js';
 import {foobarString} from '../helpers/input.js';
 import {subprocessSendGetOne, subprocessExchange} from '../helpers/ipc.js';
+import {PARALLEL_COUNT} from '../helpers/parallel.js';
 
 setFixtureDirectory();
 
@@ -15,11 +16,9 @@ const testExchange = async (t, exchangeMethod) => {
 test('Can exchange IPC messages', testExchange, subprocessSendGetOne);
 test('Can exchange IPC messages, exchangeMessage()', testExchange, subprocessExchange);
 
-const HIGH_CONCURRENCY_COUNT = 10;
-
 const testHeavyLoad = async (t, exchangeMethod) => {
 	await Promise.all(
-		Array.from({length: HIGH_CONCURRENCY_COUNT}, async (_, index) => {
+		Array.from({length: PARALLEL_COUNT}, async (_, index) => {
 			const subprocess = execa('ipc-echo.js', {ipc: true});
 			t.is(await exchangeMethod(subprocess, index), index);
 			await subprocess;
diff --git a/test/pipe/streaming.js b/test/pipe/streaming.js
index ebdc18a8cd..bd92202a90 100644
--- a/test/pipe/streaming.js
+++ b/test/pipe/streaming.js
@@ -6,6 +6,7 @@ import {setFixtureDirectory} from '../helpers/fixtures-directory.js';
 import {foobarString} from '../helpers/input.js';
 import {assertMaxListeners} from '../helpers/listeners.js';
 import {fullReadableStdio} from '../helpers/stdio.js';
+import {PARALLEL_COUNT} from '../helpers/parallel.js';
 
 setFixtureDirectory();
 
@@ -41,12 +42,10 @@ test('Can pipe three sources to same destination', async t => {
 	t.is(await thirdPromise, await destination);
 });
 
-const subprocessesCount = 100;
-
 test.serial('Can pipe many sources to same destination', async t => {
 	const checkMaxListeners = assertMaxListeners(t);
 
-	const expectedResults = Array.from({length: subprocessesCount}, (_, index) => `${index}`).sort();
+	const expectedResults = Array.from({length: PARALLEL_COUNT}, (_, index) => `${index}`).sort();
 	const sources = expectedResults.map(expectedResult => execa('noop.js', [expectedResult]));
 	const destination = execa('stdin.js');
 	const pipePromises = sources.map(source => source.pipe(destination));
@@ -64,7 +63,7 @@ test.serial('Can pipe same source to many destinations', async t => {
 	const checkMaxListeners = assertMaxListeners(t);
 
 	const source = execa('noop-fd.js', ['1', foobarString]);
-	const expectedResults = Array.from({length: subprocessesCount}, (_, index) => `${index}`);
+	const expectedResults = Array.from({length: PARALLEL_COUNT}, (_, index) => `${index}`);
 	const destinations = expectedResults.map(expectedResult => execa('noop-stdin-double.js', [expectedResult]));
 	const pipePromises = destinations.map(destination => source.pipe(destination));