QRegularExpressionMatch memory consumption

[mvidelgauz]

Hello,
here is part of my code:
@int Parser::SomeFunction(const QString &line, int start, int& fieldStart, int& fieldLength ) const
{
int end;
......
if (0 == m_pRegExp)
{
......
}
else
{
#ifdef KNOWN_PATTERN
end = 19;
#else

    QRegularExpressionMatch match = m_pRegExp->match(line,  start);
    if (!match.hasMatch())
    {
        return 0;
    }

    // currently we are requiring match to be found exactly at the position 'start'
    if (match.capturedStart() != start)
    {
        return 0;
    }

    end = match.capturedEnd();

#endif
}
.....
}
@

The program loads a text file and parses its lines one by one. The whole purpose of code in 'else' scope is to calculate where a field ends (integer 'end') in the next line passed to the function. When I compile with KNOWN_PATTERN #defined and load some test file, for which I know 'end' should become 19, my program consumes about 400 MB less memory than when compiled without KNOWN_PATTERN #defined. 400 MB is what all lines of my test file occupy in the memory (I can can calculate it based of file size and also I watched memory consumption when file was loaded and before parsing started).
So it seems to me that QRegularExpressionMatch creates a copies of each line and does not release it.
What am I missing here?
Thanks!