no search results/404 messes up sidebar

My site is up and running fine, but I’ve set up a search page and, in testing it, I’ve discovered that if there are no search results the page will not finish loading the search page (it works fine if there are search results).
I’ve gotten a couple of different error messages:

Fatal error: Maximum execution time of 30 seconds exceeded in /home/content/o/r/a/orangestreet/html/wp-includes/functions.php on line 663

Fatal error: Maximum execution time of 30 seconds exceeded in /home/content/o/r/a/orangestreet/html/wp-content/plugins/sidebar-page-switcher.php on line 133

Also, if I try testing the 404 page by typing in a bad directory, the page mostly loads but something in the sidebar times out and produces an error:

Fatal error: Maximum execution time of 30 seconds exceeded in /home/content/o/r/a/orangestreet/html/wp-includes/cache.php on line 39

Here’s my search page: http://www.orangestreetstudio.com/help/

Any ideas would be much appreciated. I’ve set up my sidebar to contain
<?php /* If this is a 404 page */ if (is_404()) { ?> <?php } ?>