SQL Server Efficiently dropping a group of rows with millions and millions of rows

Question

I recently asked this question: MS SQL share identity seed amongst tables (Many people wondered why)

I have the following layout of a table:

Table: Star

Answer 1

Must you delete them? Often it is better to just set an IsDeleted bit column to 1, and then do the actual deletion asynchronously during off hours.

Edit:

This is a shot in the dark, but adding a clustered index on CategoryId may speed up deletes. It may also impact other queries adversely. Is this something you can test?