GC behavior

[Jonathan via Digitalmars-d]

If I pool all unused objects such that no object needs to be 
GC'ed, does it still perform scanning? What are other good ways 
to avoid its overhead? As you might tell, I know rather little 
how D's garbage collection works. I'm working on a game engine 
and trying to be as resource efficient as possible.

FYI, I've been using Rust for the last three months and decided 
to take a break from it. The documentation is far from the 
quality that D has and managing explicit lifetimes becomes a 
serious pain during mid project, especially in cases that you 
know are already safe.