Dave,
Thanks for clue I read all about clustering factor. Hmmmm Full table scan i dont think is good idea. Will reducing clustering factor help. I read 2-3 ways to do it like export import. Creating table_bkp as select * from original. then drop original and again create original. Like that will that help.

I read this article..
http://www.dizwell.com/html/clustering_factor.html

Rgds
Parag