If you're suggesting that Viliam's hypothetical world is so ridiculous -- because obviously slaves would make rotten programmers -- that there's no point asking that question, though, I can't agree.

Yes, slaves would make rotten programmers, barring some kind of society-wide slave system like the Romans had where certain types of slaves could benefit from their skills and even buy themselves out of slavery.

Sex, like programming, doesn't work best under conditions of extreme stress.

While it doesn't work best, the fact that it is a physical activity sharply limits how much worse it becomes.