Yes, Corona still relies on portals for better, faster interior renderings.
For glass you can simply check the "Thin (no refraction)" option in Refraction channel or set IOR to 1 (same thing). Which basically leaves only reflection visible & is know as "Architectural Glass" (behaves better, renders faster).
Further more, in case you're describing, glass can be excluded altogether since strong light coming into the space makes it practically "invisible" to the observer looking outside. Under such conditions it's dirt and other imperfections that reveal its presence. Unless there's a certain detail, focal point or other need for better dynamics you want to introduce to strengthen the story - alike distorted view, caustics, dispersion and so on.
