diff --git a/admin/tool/behat/cli/run.php b/admin/tool/behat/cli/run.php
index e402efa96dc..b52337b6b7e 100644
--- a/admin/tool/behat/cli/run.php
+++ b/admin/tool/behat/cli/run.php
@@ -262,8 +262,13 @@ if (empty($parallelrun)) {
     behat_config_manager::set_behat_run_config_value('lasttorun', $options['torun']);
     behat_config_manager::set_behat_run_config_value('lastfromrun', $options['fromrun']);
 
+    // Keep no delay by default, between each parallel, let user decide.
+    if (!defined('BEHAT_PARALLEL_START_DELAY')) {
+        define('BEHAT_PARALLEL_START_DELAY', 0);
+    }
+
     // Execute all commands, relative to moodle root directory.
-    $processes = cli_execute_parallel($cmds, __DIR__ . "/../../../../");
+    $processes = cli_execute_parallel($cmds, __DIR__ . "/../../../../", BEHAT_PARALLEL_START_DELAY);
     $stoponfail = empty($options['stop-on-failure']) ? false : true;
 
     // Print header.
diff --git a/lib/behat/lib.php b/lib/behat/lib.php
index 1ca3f098be2..6a1bef7151c 100644
--- a/lib/behat/lib.php
+++ b/lib/behat/lib.php
@@ -493,9 +493,10 @@ function behat_get_run_process() {
  *
  * @param array $cmds list of commands to be executed.
  * @param string $cwd absolute path of working directory.
+ * @param int $delay time in seconds to add delay between each parallel process.
  * @return array list of processes.
  */
-function cli_execute_parallel($cmds, $cwd = null) {
+function cli_execute_parallel($cmds, $cwd = null, $delay = 0) {
     require_once(__DIR__ . "/../../vendor/autoload.php");
 
     $processes = array();
@@ -519,6 +520,11 @@ function cli_execute_parallel($cmds, $cwd = null) {
             }
             exit(1);
         }
+
+        // Sleep for specified delay.
+        if ($delay) {
+            sleep($delay);
+        }
     }
     return $processes;
 }