It's a tough site to run because hundreds of thousands of people have write access to the database and reddit attempts to provide the millions of people reading the comments pages with up-to-the-fraction-of-a-second updates.

It's like running a tenth of a twitter with a 10k char limit, if twitter had 10 people on development/operations

>up-to-the-fraction-of-a-second updates.

I don't think that's true. I believe the comment pages are cached for 1 min.

I've anecdotally noticed an increase in stale pages lately as well, which I would guess is from more aggressive caching. For example, new submissions used to show up instantly, but on popular subreddits may now take a few minutes to show up on the New tab.

If someone really wants to figure it out:

https://github.com/reddit/reddit

Reading from database is hard.

To be fair, it seems to have improved dramatically in the last couple of months.