Sims 3: Aging options are greyed out

You can make a backup of your saves and then, reinstall everything.

And then, recover the backup to it's place and test.

If still with the problem:

1. Your lot or neighborhood got a problem/bug and needs to reset (Erase).
2. Check if there's an update for the game. It should help.
3. Something really strange happened and i can't help you :P

Apart from performance issues, there are a few other things that influence the speed of your Sims.

• Sims move slower when they are tired.
• Less active Sims move slower.
• Old Sims move slower than younger Sims.

You can get Sims to run, although I don't think that works with staircases.

The Sims series has never had all actions take a realistic amount of time. If everything was based on real life timing, then Sims would walk so fast it would look silly, or the current 60:1 Sim/RL time ratio would have to be lowered, and then some other actions would seem terribly slow in comparison.

Although The Sims aims to simulate real life (to a degree), sometimes it deviates from realism in order for a "better" playing experience.

As far as I am aware, there is no way to get Sims to move at a speed that is comparable to the speed at which we move in real life.