In the limit, going from first space velocity V1 (low circular orbit) to second space velocity (parabolic speed) V2 = sqrt(2) * V1 takes delta V = (sqrt(2)-1) * V1, then at infinity you do plane change to the opposite with expending zero delta V, then come back and return to the same orbit, only the opposite direction (largest speed change) spending again delta V = (sqrt(2)-1) * V1. Comparing this total of 0.82 * V1 to spending 2 * V1 if you do that on the spot - just reversing the orbital velocity in place - shows the benefit.