Ah sorry! I didn't think you meant literally "10 seconds", was assuming you just meant quickly (a few minutes).
I can't really think of a use case though where someone would need more capacity in sub 10 seconds. Maybe if you only intend to scale horizontally with a bunch of 500Mb instances and had little to no room to set an appropriate scaling threshold? What would be a couple examples? With the apps I've seen the past several years generally they have scaling thresholds at 'X' resource and 3 minutes is more than enough to provision extra capacity for their needs.
The best I've managed was ninety seconds on my own hardware and three minutes (on average) in AWS.