[coldtea]

Reaction time is irrelevant in programming -- at any specific rate of decline in one's 40s and 50s and even 60s.

Cognitive skills are not, but they're not declining in any significant rate to make any difference (some of the best programmers are old), and are balanced by experience.

Also, let's see what tune you will sing 10 or 20 years down in your career.

What the companies mostly want is to eliminate people who have personal lives, and don't care for constant death marches and bro-ing it away at the office.