ifstream performance

I'm finding that using ifstream to read in numbers from a text file runs slow in MFC applications (vc++ 6.0). This seems to be related to MFC applications being multi-threaded.

In a console application without MFC, the following code

ifstream in("test.txt");

double x;
while(!in.eof()) {
in >> x;
}

in.close();

runs 3-4 times slower when Project Settings - Code Generation "use run-time library" is Multi-threaded compared to single-threaded.

Doing the same using C functions fopen and fscanf is unaffected by these options and faster than ifstream.

Does any one know how to get around the poor ifstream performance in MFC / multi-threaded applications

James.