Is there a performance issue when creating columns in one command or in several ?

Hi,

1) I need to create 3 nullable columns in a very huge table. Is there a difference, from performance point of view, if I perform it in on SQL statement or in 3 diffrent ones (one ALTER statemet for each column) ?

2) I need to create 3 mandatory columns with default value in a very huge table. Is there a difference, from performance point of view, if I perform it in on SQL statement or in 3 diffrent ones (one ALTER statemet for each column) ?

The table is clustered.

Regards, Asi Pesa