QFIle very slow

#include <QFile>
#include <QDebug>
#include <QStringList>
#include <QCoreApplication>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QStringList args = a.arguments();
    if( 2 != args.size())
    {
        qDebug() << "Usage: " << args[0] << "FileName";
        return -1;
    }

    QFile file( args[1] );
    if ( ! file.open(QIODevice::ReadOnly ) )
    {
        qDebug() << "cound not open file " << args[1];
        return -1;
    }

    while ( ! file.atEnd() )
    {
        char c;
#if 1
        file.getChar(&c);
#else
        QByteArray data = file.read( 4096 );
        for(int i = 0 ; i < data.size() ; ++i )
        {
            c = data.at(i);
        }
#endif
    }

    return 1;
}