CTFE slower than expected

[bearophile]

Walter Bright:

> tl,dr: CTFE started out as a glorified constant folder, not an 
> interpreter. An interpreter needs a different design.

And I presume a basic JITting interpreter for CTFE (like one in 
LDC2 using existing LLVM JIT tools) needs yet another design.

Bye,
bearophile