Here’s the really short version: I used /%postname%/ as my permalink structure on CSS-Tricks for a long time. I have lots of Pages. My site went down. I changed my permalink structure to begin with a number. Now it’s fine.
And the long version:
All the sudden one evening the server that runs this site and one of my other sites, CSS-Tricks seemed to get very slow (I noticed while trying to save a draft of a post). I tried visiting the homepage and various other parts of the site and it either took a long time or just timed out completely. Always a heart-sinking time for me, as I know very little about servers and how to troubleshoot them.