Views created by SQL server Database Tuning advisor
The short answer is that it's impossible to tell, but it's not terribly likely.

Views without indexes are just obfuscated queries. Unless you've written queries directly against those views, there's generally no advantage for the optimizer to decide to use them.

The safest thing to do would be to


Script their definitions 
Script the DROP commands you plan to use
Check them into change management or source control


That way, if you drop any, and something odd happens (like queries failing), you can add them back. If you have a dev/QA environment, make the changes there first and let them burn in for a week.

I'm not sure why you brought up index creation speed. If you're under the impression that creating a view that isn't indexed requires some physical structure gets built, it doesn't.

On the flip side, the views created by DTA are often created with the SCHEMABINDING option, which makes altering the underlying tables and columns that they touch throw errors that are confusing to track down.

Hope this helps!