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.
// UK lang variables
tinyMCE.addToLang('fullpage',{
title : 'Document properties',
desc : 'Document properties',
meta_tab : 'General',
appearance_tab : 'Appearance',
advanced_tab : 'Advanced',
meta_props : 'Meta information',
langprops : 'Language and encoding',
meta_title : 'Title',
meta_keywords : 'Keywords',
meta_description : 'Description',
meta_robots : 'Robots',
doctypes : 'Doctype',
langcode : 'Language code',
langdir : 'Language direction',
ltr : 'Left to right',
rtl : 'Right to left',
xml_pi : 'XML declaration',
encoding : 'Character encoding',
appearance_bgprops : 'Background properties',
appearance_marginprops : 'Body margins',
appearance_linkprops : 'Link colors',
appearance_textprops : 'Text properties',
bgcolor : 'Background color',
bgimage : 'Background image',
left_margin : 'Left margin',
right_margin : 'Right margin',
top_margin : 'Top margin',
bottom_margin : 'Bottom margin',
text_color : 'Text color',
font_size : 'Font size',
font_face : 'Font face',
link_color : 'Link color',
hover_color : 'Hover color',
visited_color : 'Visited color',
active_color : 'Active color',
textcolor : 'Color',
fontsize : 'Font size',
fontface : 'Font family',
meta_index_follow : 'Index and follow the links',
meta_index_nofollow : 'Index and don\'t follow the links',
meta_noindex_follow : 'Do not index but follow the links',
meta_noindex_nofollow : 'Do not index and don\'t follow the links',
appearance_style : 'Stylesheet and style properties',
stylesheet : 'Stylesheet',
style : 'Style',
author : 'Author',
copyright : 'Copyright',
add : 'Add new element',
remove : 'Remove selected element',
moveup : 'Move selected element up',
movedown : 'Move selected element down',
head_elements : 'Head elements',
info : 'Information',
info_text : '',
add_title : 'Title element',
add_meta : 'Meta element',
add_script : 'Script element',
add_style : 'Style element',
add_link : 'Link element',
add_base : 'Base element',
add_comment : 'Comment node',
title_element : 'Title element',
script_element : 'Script element',
style_element : 'Style element',
base_element : 'Base element',
link_element : 'Link element',
meta_element : 'Meta element',
comment_element : 'Comment',
src : 'Src',
language : 'Language',
href : 'Href',
target : 'Target',
rel : 'Rel',
type : 'Type',
charset : 'Charset',
defer : 'Defer',
media : 'Media',
properties : 'Properties',
name : 'Name',
value : 'Value',
content : 'Content',
rel : 'Rel',
rev : 'Rev',
hreflang : 'Href lang',
general_props : 'General',
advanced_props : 'Advanced',
delta_width : 0,
delta_height : 0
});