From my high school history books and other related research, I gathered the opinion that slavery was slowly becoming too burdensome for the south and this contributed to the North's victory. Paid labor allowed the North to vastly outpace the South in Industry and Technology. Mostly the persistence of the slave owners seems pride in the face of the constant nagging of Puritan North.

Are you sure that the population of the south was 92% slave?
That figure sounds exaggerated.