Help: Take 150 seconds to parse

I'm trying to process this document - http://imwerden.de/pdf/bocharov_roman_tolstogo_vojna_i_mir_1978__ocr.pdf and it takes +-150 seconds.

Why so long ? Speed depends on font type ?

Also similar size pdf (http://gsl.mit.edu/media/programs/south-africa-summer-2015/materials/0to1.pdf) processed for 5 seconds.

const parsePdf = (filePath) => {
  let pdfParserRawText = new PDFParser(this,1);
  pdfParserRawText.loadPDF(filePath);
  
  return new Promise((resolve, reject) => {
    pdfParserRawText.on('pdfParser_dataError', errData => {
      reject(new Error(errData.parserError));
    });
    pdfParserRawText.on('pdfParser_dataReady', pdfData => {
      const rawText = pdfParserRawText.getRawTextContent();
      resolve(rawText);
    });
  });
};

No source files or tests are named. Start at PDFParser.loadPDF and getRawTextContent in the provided parsePdf entry point, then compare processing of the two linked PDFs while profiling the parser. Done means identifying and documenting the cause of the large timing difference, or narrowing it to a specific parsing stage.