[taway_1212]

I think programming as a full-time job is hard enough on the brain, and the manager's instinct of trying to squeeze extra productivity out of people should not be applied. Let people work at their own pace, if you see someone who seems to be consistently slow (say over 6 months), have a talk with him. Maybe he can put in some extra effort and the talk will make him do so - or maybe he's already at max capacity (max capacity over long term is very different than max capacity over 2-4 weeks) in which case you either accept it or fire him.

Also, if you evaluate people on speed only, ignoring quality of their work, people will eventually figure it out and the quality will of course suffer. To prevent this from happening, you'll need to pay attention to quality too, which in practice is probably even harder than tracking speed.

To summarize, IMO software development (like many other white collar jobs) is a ripe for exploitation by slackers. This cannot be entirely prevented, and can only be combated by being in the trenches with the team and careful observation of each team member's performance over the long run.