Well I'm an idiot - the fulltext index on page_text was missing from a default installation. It didn't break searches but probably slowed them down tremendously. Also set engine to MyISAM on page_text to avoid cryptic error messages from MySQL.
+ − <html xmlns="http://www.w3.org/1999/xhtml">
+ − <head>
+ − <title>blank_page</title>
+ − <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
+ − </head>
+ − <body class="mceContentBody">
+ −
+ − </body>
+ − </html>