dmd -profile=gc

[Walter Bright via Digitalmars-d]

Just merged in is a new compiler switch that instruments generated code to 
collect statistics on memory allocation usage and generates a report upon 
program termination. (Much like how -profile works.)

This was based on a prototype Andrei had written earlier.
Andrei and I suspect it can be of great use in figuring out why a program may be 
excessively slow or consume excessive memory.

I encourage giving it a try on some non-trivial project, and see if it gives 
useful information.