I am having a similar problem. I have a link on a report detailing some ticket information. That link should regenerate the same data as displayed on the page but as an excel spreadsheet that is passed to the user for download and not saved on the server.

The link works, a download dialog appears to save the file but for some reason the file appears to be limited to around 400k in size ( a little under 4500 of the 9755 rows that should appear. When I change from a file handle to saving the file to the server it works fine, the problem only happens when it's a direct download. Any help you could offer would be great

    tie *XLS, 'IO::Scalar', \$xls_str;
    my $workbook = Spreadsheet::WriteExcel::Big->new(\*XLS);
    my $worksheet = $workbook->add_worksheet();

    # Hardcoded row and column fields
    $worksheet->set_landscape();
    $worksheet->set_row(0,30);
    $worksheet->set_column(0,0, 20);
    $worksheet->set_column(1,1, 20);
    $worksheet->set_column(2,2, 20);
    $worksheet->set_column(3,3, 20);
    $worksheet->set_column(4,4, 20);
    $worksheet->set_column(5,5, 20);
    $worksheet->set_column(6,6, 20);

    # Spreadsheet Formating
    my $format = $workbook->add_format();
    my $titleformat = $workbook->add_format();
    $format->set_bold(1);
    $titleformat->set_size(15);

    # Counters
    my $rowcount = 1;

    # loops for writing
    while ( my @row = $sth->fetchrow_array ) {
      my $row_ref = \@row;
      $worksheet->write_row($rowcount,0,  $row_ref);
      $rowcount++;
    } #end of loop

    $workbook->close();

    #my $size = (-s $xls_str);
    print "content: myfile.xls\r\n";
    print "content-disposition: inline; filename=myfile.xls\r\n";
    #print "content-length: $size\r\n";
    print "content-type: application/vnd.ms-excel\r\n";

    #local $/ = undef;
    #open (F, "<$xls_str");
    #  binmode(F); binmode(STDOUT);
    #  print <F>;
    #close(F);
    print $xls_str;

in the above script if I replace

    tie *XLS, 'IO::Scalar', \$xls_str;
    my $workbook = Spreadsheet::WriteExcel->new(\*XLS);

    my $filename = "myfile.xls";
    my $workbook = Spreadsheet::WriteExcel->new($filename);

I believe the problem has something to do with IO::Scalar and/or an apache config but I'm a little lost as to what I could be missing