I fly out of SNA quite regularly too. I've never had to wait more than 15 minutes in security lines at terminal A. I almost have it down to a science.

Last time, at about 6:15 AM I park my car at work (shares the fence with the Main St. parking lot) and run into the Main St. parking. Take the shuttle to the terminal. When I get off the shuttle bus, it's about 6:25 AM. Clear security at 6:40 AM. My flight was boarding and ended up leaving the gate at 6:55 AM! Yeah, I know...I should wake up earlier in case the lines do get bad.
I've dropped friends at SNA during the weekends and have seen horrible lines outside though.
Steve