Interesting path!
To Devildude1, I also got a 4 off before -- my mistake was that I approached the lock near finish too early ... Not sure if this gives you any idea?
I was initially 30+ off when I try to make shortcuts, and when I knew I should just do things as they looked I then solved the level. Tricked me well. Haha.
If you have not done FlashBack's "Zerg Rush", please go and try it! It is more powerful than building pylons.