Fugliness
Ok, here's an excerpt from an example output. Out of 13 seconds (it's slower when profiling is on), Article::getContent takes up only 0.314916 seconds. There are 254 Article::getContents calls, but only 157 call Article::loadContent calls, and 174 Revision::loadText (this is what loads the revision text from the db) calls. Revision::loadText takes up only 0.088527 seconds, so the database is definitely not the bottleneck. The parser is. In fact, the number of wfMsgReal calls greatly concerns me...
(format is seconds count name)
13.215451 1 - -total 3.611685 26819 - wfMsgReal 3.447692 1287 - Parser::parse 3.399038 1287 - Parser::parse-OutputPage::parse 2.164450 138 - WikiEditorHooks::addModules 2.131158 1292 - Parser::internalParse 1.788212 2005 - Parser::replaceVariables 1.526407 694 - Parser::transformMsg 1.496620 694 - Parser::preprocess 1.345063 3222 - PPFrame_DOM::expand 0.996161 1142 - Parser::braceSubstitution 0.904751 3313 - Preprocessor_DOM::preprocessToObj 0.775065 1 - Setup.php 0.762118 1 - Setup.php-SetupSession 0.580727 2004 - Parser::clearState 0.411560 3308 - Preprocessor_DOM::preprocessToXml 0.314916 254 - Article::getContent 0.302848 157 - Article::loadContent 0.278424 3313 - Preprocessor_DOM::preprocessToObj-loadXML 0.274240 795 - Database::query
You're right that it's not the major cause, but if I was a DBA on a system taking 1/3s to return this little content.... I'd be concerned. Is that the only call getting content? Remember - I know nothing about MW but loadContent seems to take a while too.
I know MySQL is only an open source database, not a proper product, but I wouldn't expect a database to be taking this long over a simple query based on a very few params.
The db stuff is much less than that actually - I'll have to insert more profiling calls to figure out why loadcontent takes so long (I have an idea), but the actual db access is in Revision::loadText, which is only 0.088 seconds. The profiling info also contains all the database queries, but I didn't write them down - they were really quick, so it's definitely not the database. And even 0.3 seconds is relatively small compared to the total.