Improving IO Speed

[TJB]

I have a program in C++ that I am translating to D as a way to 
investigate and learn D. The program is used to process 
potentially hundreds of TB's of financial transactions data so it 
is crucial that it be performant. Right now the C++ version is 
orders of magnitude faster.

Here is a simple example of what I am doing in D:

import std.stdio : writefln;
import std.stream;

align(1) struct TaqIdx
{
   align(1) char[10] symbol;
   align(1) int tdate;
   align(1) int begrec;
   align(1) int endrec;
}

void main()
{
   auto input = new File("T201212A.IDX");
   TaqIdx tmp;
   int count;

   while(!input.eof())
   {
     input.readExact(&tmp, TaqIdx.sizeof);
    // Do something with the data
   }
}

Do you have any suggestions for improving the speed in this 
situation?

Thank you!

TJB