Background the hook command.

www/functions.php

@@ -168,7 +168,7 @@ MM_reloadPage(true);
         }
 
         $argstr = trim($argstr);
-        @exec("$hook_val $argstr");
+        @exec("$hook_val $argstr > /dev/null 2>&1 &");
     }
 
     function get_PI_REST($url, $p = false, $decode = true, $timeout = 300)