Building is slow!

[Ivan Trombley via Digitalmars-d]

When DUB bulds the gtk-d library, it takes a long time. This is 
mostly because it's only using one processor. It hasn't been such 
a big deal on Linux but I'm building my app on Windows right now 
and it been building gtk-d for the last half hour! Is there any 
way to make DUB use more processors?