Speeding up adding columns to a database table?

 Hello,

I want to know what happens behind the scenes when columns are added to a table in Oracle.  Are there ways to speed up this process? 

Here is a sample SQL that takes 10 hours in our SAP BW system.  Is there anything I can do to speed it up?

ALTER TABLE "/BIC/AZOSCMPOI00" 

ADD ("OI_DMBTR" NUMBER (000017, 000002) DEFAULT 0 NOT NULL ,

"DSC_AMT_LC" NUMBER (000017, 000002) DEFAULT 0 NOT NULL ,

"VALUE_LC" NUMBER (000017, 000002) DEFAULT 0 NOT NULL ,

"/BIC/ZMDMBTR" NUMBER (000017, 000002) DEFAULT 0 NOT NULL ) ...

Table Info:

Space
Allocated space..Kbyte     14,745,648
          blocks......      1,843,206
          extents.....            301
*Used blocks..........      1,512,170
*Never used blocks....              0
*Free in used blocks.%              0

Block structure
locksize.........byte          8,192