> ## Documentation Index
> Fetch the complete documentation index at: https://learn.nextedy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Troubleshooting Performance Issues

> This guide helps you diagnose and resolve slow loading or rendering in the Nextedy GANTT chart.

export const LastReviewed = ({date}) => {
  if (!date) return null;
  const formatted = new Date(`${date}T00:00:00Z`).toLocaleDateString("en-US", {
    year: "numeric",
    month: "long",
    day: "numeric",
    timeZone: "UTC"
  });
  return <p className="mt-10 text-sm text-gray-400 dark:text-zinc-500 not-prose">
      Last reviewed on {formatted}
    </p>;
};

## Diagnostic Steps

Start by checking the Gantt footer for load statistics. The footer shows key performance indicators:

| Footer Metric    | Meaning                                  | Action if High                            |
| ---------------- | ---------------------------------------- | ----------------------------------------- |
| Gantt Rows       | Number of items loaded                   | Reduce with filters or lower Max Items    |
| Skipped          | Items beyond the Max Items limit         | Increase limit or narrow query scope      |
| Server load time | Time taken to prepare data on the server | Check server resources, reduce item count |
| Errors           | Issues encountered during load           | Address errors to avoid retry overhead    |

<Steps>
  <Step title="Reduce the Item Count">
    The most impactful performance optimization is reducing the number of items the Gantt needs to load and render.

    **Narrow the dataset query:**

    Configure the widget's dataset to filter for only the relevant work items. Use Polarion Lucene queries to scope the data:

    * Filter by status (e.g., exclude closed items)
    * Filter by date range to show only current sprints
    * Filter by work item type to show only relevant types

    **Adjust Max Items:**

    Navigate to **Widget Parameters > Max Items** and set a value appropriate for your project size. The default limit prevents excessive loading, but setting it too high causes slow performance.

    <Warning title="Avoid loading 5000+ items">
      Projects with thousands of work items can cause the Gantt to load slowly or appear blank. Use dataset filters to reduce the scope before increasing Max Items. If you must display large datasets, consider splitting the view into multiple Gantt widgets, each focused on a subset.
    </Warning>
  </Step>

  <Step title="Review Custom Scripts">
    Item scripts execute for every loaded work item, so complex scripts multiply their impact across the entire dataset.

    * **Simplify item scripts** -- Remove unnecessary API calls or complex logic
    * **Avoid heavy Polarion API calls in scripts** -- Each call adds server round-trip time
    * **Check for script errors** -- Failing scripts may cause retry loops that slow loading

    <Tip title="Check for script errors in the footer">
      A triangle icon with an error count badge in the Gantt footer indicates script errors. Fixing these errors can improve performance because the Gantt avoids processing broken scripts repeatedly.
    </Tip>
  </Step>

  <Step title="Verify Configuration Alignment">
    Performance issues are sometimes caused by configuration mismatches with Polarion administration settings:

    1. **Verify enumeration values** -- Ensure that work item type IDs, link role IDs, and field IDs in the widget parameters match the values defined in **Polarion Administration**
    2. **Check field mappings** -- Invalid field references (Start Field, End Field, Duration Field) cause extra error handling during load
    3. **Review dependency roles** -- Missing or incorrect dependency roles generate errors for each affected work item
  </Step>

  <Step title="Optimize Working Calendars">
    If you use working calendars, calendar resolution adds processing time per work item. Consider:

    * Using a shared calendar project rather than per-user calendars for simpler configurations
    * Clearing the calendar cache after making calendar changes by calling the `clearCalendarCache` endpoint
  </Step>

  <Step title="Check Gantt Version">
    Newer Gantt versions include performance improvements. Check the version displayed in the Gantt footer and update if you are running an older release.
  </Step>
</Steps>

## Performance Optimization Summary

<Frame>
  <img src="https://mintcdn.com/none-17b4493f/umKaPvHwUHw-ZQFM/gantt/diagrams/guides/troubleshooting/performance/diagram-1.svg?fit=max&auto=format&n=umKaPvHwUHw-ZQFM&q=85&s=c6fb02fdfe1c12de4a2aadbe2571ba0f" alt="diagram" style={{ maxWidth: "560px", width: "100%" }} width="560" height="580" data-path="gantt/diagrams/guides/troubleshooting/performance/diagram-1.svg" />
</Frame>

## Verify

After applying optimizations, reload the Gantt chart. You should now see faster loading with the footer showing a reduced item count, zero skipped items, and no error indicators. Check the server load time in debug mode to confirm improvement.

## See also

* [Manage Large Datasets with Max Items](/gantt/guides/filtering/max-items)
* [Use Gantt Filters](/gantt/guides/filtering/gantt-filters)
* [Troubleshooting Blank or Non-Loading Gantt](/gantt/guides/troubleshooting/blank-gantt)
* [Troubleshooting Script Errors](/gantt/guides/troubleshooting/script-errors)

<LastReviewed date="2026-07-02" />