In the context of the comment I replied to, no, it's not.
Haskell gives you some constructs that makes this easier but there exists no program whose Haskell implementations will run faster because of this, only programs that are easier to make fast.
The big advantage lazy evaluation has is composability. In an eager language, you have to explicitly code operations in a lazy fashion, which means that if you use a library, it will probably be eager. With Haskell you can be pretty sure that the runtime will evaluate only as much of the program as it needs to.
That said, the downside is that it then becomes very difficult to reason about the performance characteristics of your library, because its performance depends on how it's used. Simon Peyton-Jones is on record as saying that laziness is probably the wrong default for a language - the big benefit for Haskell was that it "kept them honest" wrt purity, but in a production system you probably want strictness.
