Component based programming in D

[Bart]

I'm new to component based programming. I've read it is an 
alternative to oop for speed. I don't understand how it is 
possible to have an alternative to oop and still have oop like 
behavior(polymorphism) nor how to do this. It seems all the great 
things oop offers(all the design patterns) would be impossible. 
The benefits are suppose to better reusability as components are 
more isolated in their dependencies.

Can someone help me understand this a little better and how I'd 
go about using it in D? Specifically I'm looking at the pros and 
cons, what are the real similarities and differences to oop, and 
how one implements them in D(taking in to account D's 
capabilities).

Thanks.