copies file doesn't work well

[dreamer]

HI.
I have to copy a file, from a directory to another(changing the name).

I use the static function

QFile::copy(source,dest)

QFile::copy(source,dest)

To copy to clipboard, switch view to plain text mode 

...but, often, it doesn't make the copy(it makes the copy very late). I also remove the dest file, if one with that name exists and use the flush() function to write the buffered data.

How can i obtain a fast written on the filesystem???
I use linux with ext3.