Thank you for that advice. I'm using GDC because it's available from Ubuntu Linux's package system, whereas DMD currently is not. (And the .deb posted on digitalmars.com is only for i386.) Hopefully, D will gain more popularity and more up-to-date tools will be made available.
By the way, today I re-compiled the program with a "std.gc.enable;" right before the final "return 0" statement, and it still runs in 0.68 seconds. So either those objects aren't marked as needing garbage collection, or it's really just an issue of keeping the garbage collector from activating too quickly.
