I have the following code that performs writing into std::wofstream (with conversion into UTF-8):

std::wofstream stream;
stream.open(L"D:\\MyFile.txt", std::ios_base::app | std::ios_base::out);

std::locale utf8locale = <Get UTF-8 locale>;
stream.imbue(utf8locale);

int i;
for (i = 0; i < 700000; ++i)
{
stream.write(L"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA", 150);
}
stream.close();

This works too slowly — on computer P-4 3GHz the code (output file is 10 Mb) takes 4.1 sec.
Is it possible to accelerate it?

I have tried to large buffer for the stream (stream.rdbuf()->pubsetbuf(...)) — size of 200 Kb. But this gave no acceleration.

The compiler is MS Visual Studio 2005; Windows XP