I have a problem with a Drupal 6 site working with many nodes.
This is the SQL given by Views: https://gist.github.com/ranbogmord/79bfa50e40db1322c9e0
The query takes 5-10s to run through and the specific content-type has 30 fields bound to itself. 21 of those are exposed.
Imagine this as orders in a business system.