I found this posting after investigating a huge slowdown in a D program I'd made using gprof, which showed the culprit to be a function called _D3gcx3Gcx4markMFPvPvZv, in which the program spent 87% of its time. That turned out to be the garbage collector.
The program takes 1.74 seconds to run with two particular input files in Python. The garbage collected D version takes 5.27 seconds. The non-garbage collected version takes only 0.68 seconds. Here's a more detailed report: http://rounin.livejournal.com/21815.html Obviously, the compiled program should run at least as fast as Python, so the garbage collector could use some improvement.
