Speed & Memory Management

Hello all. I am designing a database that will could potentially grow to
have millions of tuples associated with it. My thought is that because I
will likely have many updates/inserts/deletes occurring I should set each
column that requires text to a static ammount (ie using char(30) instead of
text). However, this looks to be a double edged sword, since selecting from
the db is my largest concern (with updates a very close second). When I
pull these values back out of the db, it seems I am going to have to trim
each returned value (when I pull a ten character string out of this field,
it returns the 10 char string as well as 20 whitespaces.). I am trying to
assign a weight to each of these scenarios and figure out which is the
lesser of the two evils. If anyone has a suggestion of how I may circumvent
this issue or which possibility may work best, it would be greatly
appreciated. Thanks

Kris