Google+ post by Philipp Brüschweiler on 2016-08-16 18:00:01 UTC

Interesting - having automatically but mistakenly shut down a lot of systems, and having brought them back up again, cold cache effects meant service still took an hour and a half to get back to normal. You can’t just turn it off and on again.

Yes, the danger of caches is that you start to rely on them heavily, potentially to a point where a cold start becomes really hard.