Performant method for reading huge text files

[Rene Zwanenburg]

On Monday, 3 February 2014 at 23:50:54 UTC, bearophile wrote:
> Rene Zwanenburg:
>
>> The problem is speed. I'm using LockingTextReader in 
>> std.stdio, but it't not nearly fast enough. On my system it 
>> only reads about 3 MB/s with one core spending all it's time 
>> in IO calls.
>
> Are you reading the text by lines? In Bugzilla there is a 
> byLineFast:
> https://d.puremagic.com/issues/show_bug.cgi?id=11810
>
> Bye,
> bearophile

Nope, I'm feeding it to csvReader which uses an input range of 
characters. Come to think of it..

Well this is embarassing, I've been sloppy with my profiling :). 
It appears the time is actually spent converting strings to 
doubles, done by csvReader to read a row into my Record struct. 
No way to speed that up I suppose. Still I find it surprising 
that parsing doubles is so slow.