How to effectively process lot of objects on a list on server side

I have a List which contains a lot of objects. The problem is that i have to process these objects (process includes cloning, deep copy, and making DB calls, running business logic etc etc.

Doing this in a normal fashion, first come first serve is really time consuming and in a web application , this generally results in transaction timeouts at the server side (as this processing is anync from client perspective).

How do i process those objects so as to take minimal time and not overload the DB.