Clearly slow and thoughtful is not the way to play, but lightining fast doesnt mean better...Neither does 8 tables... I think everyone agrees that their bb/100 decreases as they take on more and more tables..of course 2-3 is very managable.
Answer
lay as fast as you believe you can still make quality decsions. A lot of these lightining fast players are putting in 40hr weeks...over a long period of time too