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copied!<p>As far as initial loading goes, I found it neccessary to extend the public API to dramatically improve large # of column loading - we're talking minutes to under a second. That said, I have similar issues with scrolling performance, even 500+ columns is really slow to scroll. </p> <p>Setting columns within my derived datagrid:</p> <pre><code>var columns = new DataGridColumnCollection(true, dataGrid); for (int i = 0; i < pivotTable.DetailsColumnCount; i++) { if (!pivotTable.NullColumns.Contains(i)) { columns.Add(new PivotDetailColumn(pivotTable, i)); } } columns.ForceUpdate(); dataGrid.Columns = columns; dataGrid.ItemsSource = Enumerable.Range(0, pivotTable.DetailsRowCount) .Where(i => !pivotTable.NullRows.Contains(i)) // Only non null rows .ToList(); </code></pre> <p>Fixes to DataGridColumnCollection:</p> <pre><code>public class DataGridColumnCollection : ObservableCollection<DataGridColumn> { private bool _DeferColumnChangeUpdates = false; public DataGridColumnCollection(bool deferColumnChangeUpdates, DataGrid dataGridOwner) : this(dataGridOwner) { _DeferColumnChangeUpdates = deferColumnChangeUpdates; } public DataGridColumnCollection(DataGrid dataGridOwner) { Debug.Assert(dataGridOwner != null, "We should have a valid DataGrid"); DisplayIndexMap = new List<int>(5); _dataGridOwner = dataGridOwner; RealizedColumnsBlockListForNonVirtualizedRows = null; RealizedColumnsDisplayIndexBlockListForNonVirtualizedRows = null; RebuildRealizedColumnsBlockListForNonVirtualizedRows = true; RealizedColumnsBlockListForVirtualizedRows = null; RealizedColumnsDisplayIndexBlockListForVirtualizedRows = null; RebuildRealizedColumnsBlockListForVirtualizedRows = true; } #region Protected Overrides public void ForceUpdate() { if (DisplayIndexMapInitialized) { UpdateDisplayIndexForNewColumns(this, 0); } InvalidateHasVisibleStarColumns(); } protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e) { switch (e.Action) { case NotifyCollectionChangedAction.Add: if (!_DeferColumnChangeUpdates) { if (DisplayIndexMapInitialized) { UpdateDisplayIndexForNewColumns(e.NewItems, e.NewStartingIndex); } InvalidateHasVisibleStarColumns(); } break; </code></pre>

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