Looking at the data, it's pretty much the same month over month in terms of quantity of posts/comments. We did institute the cost increases for excessive posting/commenting so that probably has decreased some.

You might be onto something about the topics being overly familiar though. 

k00b

Daily discussion thread

saloon

For some weird reason it feels like Stacker News slowed down in posts/comments/interactions. But the numbers don't actually show that it does... Idk why it feels like this, maybe It's because of more quantitative posts about the same topics again and again, maybe I'm just plain mistaken.