Smallville
 

I'm watching smallville beginnings(smallville season 1) havent watched other episodes. I find myself liking Lex, hope he turns out good in this storyline.
I know this is a comic book story but it occurred to me, they show Clark doing stuff at superhigh speed - cleaning, pulling sofa so Lex doesnt get hurt, and knocking Lex's attacker out. This means he can observe think and react at superhigh speed. So his thought process must be running at superhigh speed. So technically he has unlimited "thinking time" at his disposal. Woodnt that make him like really really smart?

I think your reading too much into the whole thing. ;)

I thought Superman has super physical abilities but he is just normal human intelligence.

All he would really need to be able to do his super speed stuff effectively would be really fast reflexes and good powers of observation. Neither one of which necessarily makes someone a genius.

Maybe not a genius, just really quick thinker. Effectively he can slow down time in his head. He can go through a book in the blink of an eye, he can solve problems in microseconds.