OK, let's be fair. The site has 60K+ posts (http://scrollost.com). I added a QMT toolbox to the top of every page (not in the loop) with 4 taxonomies at first and then tried reducing it to 2. That is to the top of taxonomy pages and posts.
My taxonomy pages - the last 5k posts are built via supercache (not preload) an xml site map and a third party preloader via an hourly cron that uses the sitemaps.
Before adding QMT (and after removing the code) the site works very well, but with the QMT toolbox, building the posts cache seems to crash the site. Only new posts were built.
I admit this is an extreme use of everything, but wanted to give you feedback about the problems.
Through trial and error I am discovering that many plugins break wordpress sites with extreme amounts of posts. Nevertheless I figured maybe there is a way to somehow optimize the code so this doesn't happen. In the meantime I will add the toolbox to a new front page.