C++/Cli loading text file fast as possible

Firstly I'm new at programming. I want to load CSV files, i have coded below code but its took to load 100mb file for 3-5 mins(multi threaded, single thread 5+ mins). In excel its just few secs and bulkinserting to cells. My CSV file format is;

"title1","title2","title3","title4"...
"1","1_werwq","","","myname","this a sentence with comma,,,,,",""... 

i couldn't use OLEDBCONNECTION it not loading properly so i coded this;

private: System::Void backgroundWorker1_DoWork(System::Object^  sender, System::ComponentModel::DoWorkEventArgs^  e) {
    StreamReader^ file = gcnew StreamReader(openFileDialog2->FileName, Encoding::Default, true);

    String^ columnNames = file->ReadLine();
    std::wstring ws = marshal_as<std::wstring>(columnNames);
    std::vector<std::wstring> vws;
    seperate(ws, vws);
    for (auto & s : vws) {
        DataColumn ^clm = gcnew DataColumn(gcnew String(s.c_str()));
        clm->DefaultValue = String::Empty;
        alldata->Columns->Add(clm);
    }
    setColumnNames();

    int ilines = 0;
    while (!file->EndOfStream) {
        iList->Add(file->ReadLine());
        ilines++;
    }
    ParallelOptions^ ops = gcnew ParallelOptions();
    ops->MaxDegreeOfParallelism = Environment::ProcessorCount * 2;
    CancellationTokenSource ^cts = gcnew CancellationTokenSource();
    CancellationToken ^ct = cts->Token;
    ops->CancellationToken = cts->Token;
    //Parallel::ForEach(iList, gcnew Action<iStringList^>(this, &MyForm::readStr));
    System::Diagnostics::Stopwatch ^sw = gcnew System::Diagnostics::Stopwatch();
    sw->Start();
    Parallel::For(0, iList->Count, ops, gcnew Action<int>(this, &MyForm::readStr));
    sw->Stop();



}


private: System::Void readStr(int index) {
    try {
        String^ str = iList->getLine(index);
        std::wstring aline = marshal_as<std::wstring>(str);
        std::vector<std::wstring> wlines;
        seperate(aline, wlines);

        DataRow^ oDataRow = getnewRow();

        int i = 0;
        for (auto &c : wlines) {
            String^lan = gcnew String(c.c_str());

            oDataRow[i] = lan;
            i++;

        }
        backgroundWorker1->ReportProgress(1);
        setRow(oDataRow);

        iList->performStep();
    }
    catch (...) {
        toolStripStatusLabel2->Text = "HATAAAAAAAAAAAA";
    }
}

How excel loading files so fast and bulkinsert to cells without memory leak? i tried native code but its takes alot ram...my Data files can reach 2000 columns and 20k rows. Thank you for help.