I live off of I-15 and it can be the quicker route. I'm roughly half way between SD and Anaheim, the long way as I put it. It takes an hour and 15 minutes or so to get to DL or to the Sea World area of SD. So driving from SD to Anaheim would take roughly 2 and a half hours from the 15, but there's usually less traffic and it's still a pretty drive. If you're coming from SD heading to Anaheim you want to wait until late morning (after 9 am) to head this direction, though because the 91 freeway can be the world's longest parking lot (and the 15 in south Corona isn't a picnic either). If you are going to take this route from the DL area to SD, don't wait until afternoon (between 2 and 7 pm) because it's the same problem.