D is supposed to compile fast.

[Jonathan M Davis]

On Friday, November 23, 2018 11:13:24 AM MST H. S. Teoh via Digitalmars-d-
learn wrote:
> All in all, though, the fact that we're complaining about extra seconds
> in compilation times still does show just how fast D compilation can be.
> In the old days, compiling large C++ codebases usually means 30 mins to
> 2 hours, and a few extra seconds won't even be noticed.  I haven't
> checked C++ compile times recently, though -- things may have improved
> since I last seriously used C++.

When I was a student, I worked for a while at a company that had a large C++
code base that took over 3 hours to compile from scratch (incremental builds
were an absolute must). I ended up working somewhere else for a while and
then coming back again, and in the interim, they had begun redoing the
program in Java. The build process then took about 10 minutes, and folks
were complaining about it taking too long. After having been away for a
while, my perspective was that it was a _huge_ improvement, but since they'd
been working with it for a while, the 10 minutes was annoying. So, a lot of
it comes down to perspective.

D is often a _huge_ improvement when you first switch to it, but depending
on what your code does, over time, it can go from under a second to a few
seconds in compilation time, and for some folks that becomes maddening in
spite of the fact that the overall build times are a huge improvement over
what they would have had in another language - and usually, the features
that slow down the build the most are ones that don't even exist in other
languages (or if they do, are far less powerful). That being said, if we can
reasonably improve the compiler and standard library such that D code in
general builds faster with all of the CTFE and templates, we definitely
should.

- Jonathan M Davis