Optymalizacja pamięci

vector < std::vector < std::string >> comboArray;

void tokenize( const std::string & s, const char delim, std::vector < std::string >& out )
{
    std::string::size_type beg = 0;
    for( auto end = 0;( end = s.find( delim, end ) ) != std::string::npos; ++end )
    {
        out.push_back( s.substr( beg, end - beg ) );
        beg = end + 1;
    }
   
    out.push_back( s.substr( beg ) );
}

void loadComboList()
{
    //std::filesystem::current_path();
    std::ifstream comboFile( ".\\combo.txt", ifstream::in );
    if( comboFile.is_open() )
    {
        const char explode = ':';
        string line;
        while( getline( comboFile, line ) )
        {
            std::vector < std::string > ArrayAccount;
            tokenize( line, explode, ArrayAccount );
            comboArray.push_back( ArrayAccount );
        }
    }
    else
    {
        cout << "error";
    }
}