I'm getting the following timeout errors on pages with a lot of Drupal function calls:

[Sun Jan 25 15:22:19 2009] [error] PHP Fatal error:  Maximum function nesting level of '100' reached, aborting! in /Library/WebServer/Documents/bills/includes/common.inc on line 576
[Sun Jan 25 15:22:19 2009] [error] PHP Stack trace:
[Sun Jan 25 15:22:19 2009] [error] PHP   1. {main}() /Library/WebServer/Documents/bills/index.php:0
[Sun Jan 25 15:22:19 2009] [error] PHP   2. menu_execute_active_handler() /Library/WebServer/Documents/bills/index.php:18
[Sun Jan 25 15:22:19 2009] [error] PHP   3. call_user_func_array() /Library/WebServer/Documents/bills/includes/menu.inc:348
[Sun Jan 25 15:22:19 2009] [error] PHP   4. visualize_backtrace_generate() /Library/WebServer/Documents/bills/includes/menu.inc:0
[Sun Jan 25 15:22:19 2009] [error] PHP   5. krumo() /Library/WebServer/Documents/bills/sites/all/modules/visualize_backtrace/visualize_backtrace.module:1334
[Sun Jan 25 15:22:19 2009] [error] PHP   6. call_user_func_array() /Library/WebServer/Documents/bills/sites/all/modules/devel/krumo/class.krumo.php:1276
[Sun Jan 25 15:22:19 2009] [error] PHP   7. krumo::dump() /Library/WebServer/Documents/bills/sites/all/modules/devel/krumo/class.krumo.php:0
[Sun Jan 25 15:22:19 2009] [error] PHP   8. krumo::_dump() /Library/WebServer/Documents/bills/sites/all/modules/devel/krumo/class.krumo.php:582
[Sun Jan 25 15:22:19 2009] [error] PHP   9. krumo::_array() /Library/WebServer/Documents/bills/sites/all/modules/devel/krumo/class.krumo.php:790

Solution would be to possible tie the end row into the the section argument so that it's not loading in everything.
It's likely in the theming section too where there's a lot more calls
And it's also possible that I should be using a more filtered version of the function call stack as some of the filtering that's being done is happening what was originally intended to just be a *.dot output file.