First, bear in mind that there's no way to obtain or return an AST, so you're extremely limited in terms of what you can provide in a DSL. If you want to do anything beyond a certain level of complexity, the library user will have to pass in everything as string literals, and even then there are issues; your library's API will be indistinguishable from one that operates at runtime, but be much harder to implement, for starters.

Additionally, though this may have changed since, last time I used D extensively the CTFE was plagued by performance issues and memory leaks. In fact, it was ran with no GC at all.