How disruptive is the GC?

[Snape via Digitalmars-d-learn]

I'm in the early stages of building a little game with OpenGL (in 
D) and I just want to know the facts about the GC before I decide 
to either use it or work around it. Lots of people have said lots 
of things about it, but some of that information is old, so as of 
today, what effect does the GC have on the smooth operation of a 
real-time application? Is it pretty noticeable with any use of 
the GC or only if you're deallocating large chunks at a time?