On 26 Feb 2016 9:45 am, "Walter Bright via Digitalmars-d" <digitalmars-d@puremagic.com> wrote:
>
> On 2/26/2016 12:20 AM, Iain Buclaw via Digitalmars-d wrote:
>>
>> I thought that mulithreaded I/O did not change anything, or slowed compilation
>> down in some cases?
>>
>> Or I recall seeing a slight slowdown when I first tested it in gdc all those
>> years ago.  So left it disabled - probably for the best too.
>
>
>
> Running one test won't really give much useful information. I also wrote:
>
> "On a machine with local disk and running nothing else, no speedup. With a slow filesystem, like an external, network, or cloud (!) drive, yes. I would also expect it to speed up when the machine is running a lot of other stuff."

Ah ha. Yes I can sort of remember that comment.

One interesting line of development (though would be difficult to implement) would be to do all three semantic passes asynchronously using fibers.

If I understand correctly, sdc already does this with many cases that need ironing out.