Just playing with numbers, i tried and cut cost of LargeInteger 
printString from n to (n log: 2) with a divide and conquer like method, 
reverting to SmallInteger fast arithmetic asap.

Experiment is at http://bugs.squeak.org/view.php?id=6887

I'm just following the steps of Goran at 
http://bugs.squeak.org/view.php?id=6512

Of course, LargeInteger are not as frequent as Small ones, so added 
value is limited. But the challenge was fun.

If you want to test or further improve, welcome.

Nicolas