We know that Klein said that Clark could live a long time before starting to age. Even with giving up some years to Jimmy.
What if every time Clark does something at super speed, he ages accordingly? I have always thought that just because Clark can clean an entire room in seconds flat from our POV, that doesn't mean that it was only "seconds" from his POV. His mind and body had to ramp up metabolically to accomplish the act. What if his body aged faster because of that? Then he could age more normally.
Just food for thought.
James
