While it does suck that courts take a long time, I feel like you're overemphasizing the "deterrent" effect of criminal punishment. While fear of repercussions is a non-zero factor in whether a person commits a crime, it isn't the ONLY factor, and I'd argue that for most people, it isn't even the biggest one.

Punishing people more quickly might help some surface level things, but really we should be looking at why people are motivated to commit crimes (at all levels).