Multiple-View Query Optimisation
Views are just stored queries: you don't execute views, but you SELECT data out of them. When you combine multiple views joining them, you are doing nothing different from inlining the view definition in the query. In fact, that's what the optimizer does: it's called view expansion.

If your views will never be used in isolation, but always joined together instead, I suggest that you stop tuning them individually, but you concentrate on the overall query that will use them. The optimizer will expand the views and generate a plan that will have nothing to do with the plan used when selecting from the individual views.

On the other hand, what makes your individual views faster (well-thought T-SQL code, indexes, statistics) won't probably hurt the performance of the overall query. Just don't expect the resulting plan to be a simple merge of the individual views' plans.