In the evening, I can get home as quick as 25 minutes on the 91 toll lanes. Several people in my ward that commute to Newport, Irvine or mission viejo take either the 241 toll road, the metro link train, or vanpool.
On the 241 toll I would say 35 to 40 minutes in the morning to Laguna and 50 or more coming home. I have a buddy that owns a pizzeria in mission viejo, I could ask him to be sure.
It does depend where in corona you live.
Even paying $300 a month in tolls I would guess you would still save $1000 a month in housing.
Feel free to board mail me with any questions.