I have had good luck with security barrier views and performance. The main thing security barrier does is ensure that where statements are processed correctly.
The big consideration IMHO is how many tenants are you dealing with. A couple of tenants, then best to give them separate databases. More than a couple, but less than 50 or so, then best to give them all separate schemas. If there are thousands of tenants (like an internet application) then security barrier views are usually the easiest option to manage.
