[bobnamob]

I can back up your anecdote.

For <business reasons> we have in the order of 10^6 SNS topics in one account+region pair. In that account, while in that region, the SNS console is entirely frozen. I suspect they're doing some looped pagination polling in the background and fall over on our degenerate use case.

Edit: I can also back up the other parent comment - tagging still works fine (and I know for a fact the stability and scalability of the tag system is taken more seriously than most things within AWS)