diff --git a/src/polyfills/cpus.ts b/src/polyfills/cpus.ts
new file mode 100644
index 00000000..633ee74e
--- /dev/null
+++ b/src/polyfills/cpus.ts
@@ -0,0 +1,9 @@
+import {
+  availableParallelism as nodeAvailableParallelism,
+  cpus,
+} from 'node:os';
+
+export const availableParallelism = (): number =>
+  typeof nodeAvailableParallelism === 'function'
+    ? Math.floor(nodeAvailableParallelism() / 2)
+    : (cpus()?.length ?? 1);
diff --git a/src/services/run-tests.ts b/src/services/run-tests.ts
index 50031fc4..b9a8daf9 100644
--- a/src/services/run-tests.ts
+++ b/src/services/run-tests.ts
@@ -14,6 +14,7 @@ import { format } from './format.js';
 import { runTestFile } from './run-test-file.js';
 import { isQuiet } from '../parsers/output.js';
 import { results } from '../configs/poku.js';
+import { availableParallelism } from '../polyfills/cpus.js';
 
 const cwd = processCWD();
 
@@ -101,7 +102,7 @@ export const runTestsParallel = async (
     ? [sanitizePath(dir)]
     : await listFiles(testDir, configs);
   const filesByConcurrency: string[][] = [];
-  const concurrencyLimit = configs?.concurrency || 0;
+  const concurrencyLimit = configs?.concurrency ?? availableParallelism();
   const concurrencyResults: (boolean | undefined)[][] = [];
   const showLogs = !isQuiet(configs);