Three hour waits are pretty rare at DL. Even in the summer the listed wait time for Racers is generally 2 hours. I'd expect in October to have lighter morning hours with heavier evening hours as our experience has been that many locals visit the park after work/school hours. Make sure you get there for rope drop and enjoy the mornings.
If I was trying to pick a less busy time of year I'd go with late April, so long as Easter isn't late that year, which it's not in 2016. You could run into ride closures, but most rides are open from winter refurbs by Spring Break, except last year. I actually think the last week of June is a pretty good time to visit. Crowds do pick up a bit, but the grad nights are over and there are blackout dates for a lot of locals. The park hours and open rides are at maximum.