I found the website running slowly today.
After updating a few modules and clicking "continue" on the update.php page, I get the following error:
Fatal error: Maximum execution time of 60 seconds exceeded in includes/file.inc on line 2053
I have seen other people increasing the max execution time without success.
I emptied the cache and now only receive a WSOD.
I don't see anything unusual in the Drupal logs.