One of the postulated reasons for why older people have worse reaction times and think slower than their younger counterparts is that the neural networks they use draw upon more stored information, thus making routine evaluations take longer.
There's a sweet spot between knowing enough and knowing little enough so that you get the right answer and get it quickly enough.
I guess you haven't heard of ISRIB (integrated stress response inhibitor). This drug when given to mice causes both old and alzheimer's riddled mouse brains to return to near normal. Interestingly the patent is now held by an ALPHABET company. Not saying there isn't a limit to our storage capacity, but this drug make it clear that age alone doesn't prevent the brain from working well.
There's a sweet spot between knowing enough and knowing little enough so that you get the right answer and get it quickly enough.