Odd script timeout issue. Can native define() or dirname() functions hang?

I've started getting sporadic reports of script timeout errors when users are submitting ticket changes. The error code points to line 11 in activecollab\angie\classes\swiftmailer\Swift\ClassLoader.php, a seemingly benign line of code:

if (!defined("SWIFT_ABS_PATH")) define("SWIFT_ABS_PATH", dirname(__FILE__) . "/..");

I've never run into any issue with these two native functions, but I'm wondering if it might be an obscure permissions error or something. Any have any ideas?

The exact error message was "Fatal error: Maximum execution time of 30 seconds exceeded". Looking at the PHP error log for the past month, I'm seeing a lot of that type of message, most pointing at similarly benign code. Some examples:

Maximum execution time of 30 seconds exceeded in C:\web\wwwroot\activecollab\angie\classes\NamedList.class.php on line 6

class NamedList extends AngieObject {

Maximum execution time of 30 seconds exceeded in C:\web\wwwroot\activecollab\application\modules\system\models\search_engines\MysqlSearchEngine.class.php on line 3

require_once SYSTEM_MODULE_PATH . '/models/search_engines/SearchEngine.class.php';

(There was no other error message here, such as one that might suggest the SYSTEM_MODULE_PATH constant was undefined, or that the include file couldn't be found.)

Maximum execution time of 30 seconds exceeded in C:\web\wwwroot\activecollab\angie\classes\cache\backend\FileCacheBackend.class.php on line 65
Maximum execution time of 30 seconds exceeded in C:\web\wwwroot\activecollab\angie\classes\cache\backend\FileCacheBackend.class.php on line 72
Maximum execution time of 30 seconds exceeded in C:\web\wwwroot\activecollab\angie\classes\cache\backend\FileCacheBackend.class.php on line 115
Maximum execution time of 30 seconds exceeded in C:\web\wwwroot\activecollab\angie\classes\cache\backend\FileCacheBackend.class.php on line 132
Maximum execution time of 30 seconds exceeded in C:\web\wwwroot\activecollab\angie\classes\cache\backend\FileCacheBackend.class.php on line 167

 65.        if(is_file($path)) {

 72.        } // if

115.      if(is_file($path)) {

132.      while(($entry = $d->read()) !== false) {

167.      } // foreach

There are many more of the same. I will try to compile some more examples.

I did clear the cache out yesterday. I don't suspect any file system/permissions issues because the cache files are being regenerated. I will refresh the permissions, re-clear the cache and continue to monitor.