DMD release build being faster than debug!

[Seb]

On Friday, 5 October 2018 at 14:11:22 UTC, Per Nordlöw wrote:
> I just noticed that building DMD~master via
>
>     make -f posix.mak BUILD=debug
>
> currently takes 3.2 secs while building it via
>
>     make -f posix.mak BUILD=release
>
> takes only 3.0 secs on my Ubuntu 18.04 64-bit machine!
>
> Are there more DMD switches other than `BUILD=release` I need 
> to activate to produce the fastest possible compiler binary? 
> Apart for compiling it with LDC, that is.

Yeah BUILD more or less only defines in which folder the binaries 
will be stored as the default BUILD was RELEASE historically and 
the real release build can take a while and shouldn't be used by 
default (bad newcomer experience).
We tried to change the default BUILD to debug but it was a mess 
with the CIs :/