title: Trying to improve performance of generating xls reports using DynamicJasper. Any suggestions in this direction?
body: <p><strong>Current stats:</strong>  </p>
  
  <p>Generating a .xls file containing 3 tables, each of one containing 100K rows x 3 columns took ~24s with the following breakdown:</p>
  
  <ul>
  <li>building the JRXlsExporter - ~6s</li>
  <li>JRXlsExporter.exportReport() - ~18s</li>
  </ul>
  
  <p>The code was executed on the following hardware: i7 6core CPU, 16GB RAM, SSD storage. The maximum heap size for the JVM was set to 4GB.</p>
  
  <p>Adding a snippet just to give you some insight on how I'm adding multiple tables. I'm using in-memory datasources for populating the tables.</p>
  
  <pre class="lang-java prettyprint-override"><code>DynamicReportBuilder drb = new DynamicReportBuilder();
  ...
  DynamicReport subReport = this.createSubreport(report.getSubReports()[i]);
  String dsName = String.valueOf(i);
  drb.addConcatenatedReport(subReport, new ClassicLayoutManager(),
                      dsName, DJConstants.DATA_SOURCE_ORIGIN_PARAMETER,
                      DJConstants.DATA_SOURCE_TYPE_COLLECTION, false);
  ...
  </code></pre>
  
  <p><strong>DynamicJasper version:</strong>  </p>
  
  <ul>
  <li>dynamicjasper: <strong>5.1.0</strong>  </li>
  <li>jasperreports: <strong>6.3.0</strong>  </li>
  <li>dynamicjasper core fonts: <strong>1.0</strong>  </li>
  </ul>
  
  <p><strong>So far tried the following options:</strong>  </p>
  
  <ul>
  <li>played with virtualization: <strong>no virtualization</strong>, <strong>JRSwapFileVirtualizer</strong>, <strong>JRGzipVirtualizer</strong> and <strong>JRFileVirtualizer</strong>. Best times have been registered using <strong>JRSwapFileVirtualizer</strong> (this is the one used for the provided stats)</li>
  <li>tried changing <strong>net.sf.jasperreports.text.measurer.factory</strong> with <strong>com.jaspersoft.jasperserver.api.engine.jasperreports.util.SingleLineTextMeasurerFactory</strong> [1] but wasn't able to find any source code for <strong>SingleLineTextMeasurerFactory</strong> .  </li>
  </ul>
  
  <p>[1] <a href="https://community.jaspersoft.com/wiki/how-modify-jasperreportsproperties-file-disable-multi-line-data-processing" rel="nofollow noreferrer">https://community.jaspersoft.com/wiki/how-modify-jasperreportsproperties-file-disable-multi-line-data-processing</a>  </p>