Faster Virtual Method Dispatch

[Craig Black]

> The nice thing about D, as a language, is that it supports both 
> approaches. The bad thing, for your needs, is that phobos is tightly bound 
> to the GC. My particular gripes are with the GC activity caused via utf 
> conversions, std.string and so on. There's a surprising, perhaps 
> troublesome, amount of GC activity generated from within phobos itself. 
> This is one of the reasons alternative libraries exist.

Correct.  But since the language core relies on Phobos I don't think that 
there is a reasonable way to completely decouple D from GC.  To me this 
situation is quite ugly.  It would be nice if there was a way to replace 
Phobos completely.  After writing standard libraries that don't rely on GC, 
we could easily produce D non-GC vs. D GC benchmarks.

Some steps would have to be taken in order to keep some source compatibility 
between the two modes, so that it would't turn into two completely different 
languages.  Manual memory management code could be versioned out when 
compiled in GC mode.

-Craig