Well, I’m better than I thought. I saw through the code and it seems, that wp_getPages() for no understandable reason incorporates the whole function wp_getPage. It gets _ALL CONTENT_ for _ALL PAGES_. Isn’t that a bit too much of an overhead?
Well, inside of xmlrpc.php I copied wp_getPage() and renamed it to wpgetPage2(). Then I changed inside of wp_getPage2():
$full_page = get_extended($page->post_content);
into
$full_page = “no”;
inside of wp_getPages() I changed all occurences of wp_getPage() into wp_getPage2().
I know. its a lousy hack, but it does the job. What I don’t understand, by the way, is why the function prints “n” instead of “no” in Windows Live Writer (not that it is very important).
However, it would be nice, if the wordpress-team could incorporate a better solution for the problem. I really don’t see, why wp_getPages has to collect this amazing amaount of data, just to print a small table listing the pages.