That's the beauty of serving mostly read-only data - you can just cache the most frequented pages. I can't think of a time that I clicked on a link for Stack Exchange that wasn't served via a search engine. I've never purposefully clicked a link from within Stack Exchange, and I've never posted any answers. I can thank those who do for enabling my success in my career, but I'm willing to bet that most Stack Exchange users are just like me.

These became so distracting that I applied an Adblock filter to hide the “Hot Network Questions” div, lol!

Ha! I do this too. Just the other day I was pair programming with someone who asked "why don't you have those super stupid questions on the right nav bar?"

That sidebar is my biggest time waster in the day.

They changed it so you can hide hot network questions(without any karma requirement)

Thanks for pointing that out! Direct link for anyone else looking for it: https://stackoverflow.com/users/preferences

I guess it's finally time to create an account!

Well, thanks a lot, now I have no other choice but to google at least two of those.

That shadowfax one, quora is horrible that way too. You're interested in one bit of canon triva one time, and the site immediately assumes that particular story is all you want to read about, every day for months.

I bet gwaihir carried shadowfax to valinor.

I don't think hot questions are tailored at all, are they? I often get questions from boards I never visited, so I assumed it's a global collection.

Also, caching at the correct granularity. I've seen too many systems that cache on a fine grained level and performance drops because because there are so many cache lookups, even with an in memory cache.