The compiled code for Java SWT+JFace swt.jar 1.9 MB jface.jar 0.95 MB I would expect that this code ported to D should result in a smaller amount of code. Java hold all the reflection information, D not. Afaik jar is a zip without using compression. A compiled DWT app as .exe is about 7 MB and using JFace 14 MB. Why is that? How can it be done better?