New to Telerik Document Processing? Start a free 30-day trial

Performance Tips and Tricks

Updated on Sep 8, 2026

RadSpreadProcessing lets you prepare and modify tabular data. The library is optimized for performance, but large datasets can still slow workbook operations. The following tips help you improve speed and lower resource use.

Use the following techniques when you work with large workbooks:

Reduce Layout Updates Frequency
Reduce the Number of Undo Steps
Disabling History
Apply Values or Formatting on Large Range at Once
Avoid Using the Additional Calculations Options Provided by the Shapes and Images
Avoid Cell Value Type Parsing

Reduce Layout Updates Frequency

Layout calculation determines column widths, row heights, text size, and other values that affect document layout. A layout update runs after each property change, and it can be expensive.

RadSpreadProcessing reduces layout recalculations internally, but large batch updates can still trigger extra work. If you generate a document before you display or export it, suspend layout updates until the batch operation ends. The following code snippet shows this approach.

Example 1: Suspend layout updates during document generation

Workbook workbook = new Workbook();
workbook.SuspendLayoutUpdate();
//The code which generates the document
workbook.ResumeLayoutUpdate();

If an exception occurs between the two method calls, ResumeLayoutUpdate() will not run. Use UpdateScope to make sure layout updates resume even when an exception occurs.

Example 2: Suspend layout updates with UpdateScope

Workbook workbook = new Workbook();
			using (new UpdateScope(workbook.SuspendLayoutUpdate, workbook.ResumeLayoutUpdate))
			{
				//The code which generates the document
			}

Reduce the Number of Undo Steps

Tracking undo steps is usually inexpensive, but repeated operations can still affect performance. If you do not need each change as a separate undo action, group related changes into one undo step. For example, when you set a background color for all even rows, you can save all changes in a single undo group.

Example 3: Combine multiple changes in one undo group

Workbook workbook = new Workbook();
			workbook.History.BeginUndoGroup();
			//The code which generates the document
			workbook.History.EndUndoGroup();

If an exception occurs between the two method calls, EndUndoGroup() will not run. Use UpdateScope to make sure the undo group closes correctly.

Example 4: Combine undo operations with UpdateScope

Workbook workbook = new Workbook();
			using (new UpdateScope(workbook.History.BeginUndoGroup, workbook.History.EndUndoGroup))
			{
				//The code which generates the document
			}

Disabling History

As described in Reduce the Number of Undo Steps, history tracking can lower performance in large-generation scenarios. If you do not need history while you generate a document, turn it off temporarily. The following example toggles the IsEnabled Boolean property.

Example 5: Disable history while generating a workbook

workbook.History.IsEnabled = false;
//The code which generates the document
workbook.History.IsEnabled = true;

If an exception occurs before you enable history again, later changes will not be recorded. Use UpdateScope to restore the previous state reliably.

Example 6: Disable and restore history with UpdateScope

using (new UpdateScope(
		() => { workbook.History.IsEnabled = false; },
		() => { workbook.History.IsEnabled = true; }))
{
	//The code which generates the document
}

Apply Values or Formatting on Large Range at Once

Applying the same value or formatting to thousands of cells one by one takes more time than updating a full range. Create a CellRange by using the row and column indexes of the start and end cells through the CellRange(int fromRowIndex, int fromColumnIndex, int toRowIndex, int toColumnIndex) constructor.

Avoid Using the Additional Calculations Options Provided by the Shapes and Images

When you set properties on an image, some members recalculate other values to improve UI-oriented behavior. For details, see how shapes and images work. If you generate a document from scratch, these extra calculations are usually unnecessary. In this case, use the following properties of the shape classes:

Width
Height
RotationAngle

Avoid the following methods when the adjustCellIndex parameter is true:

SetWidth()
SetHeight()
SetRotationAngle()

Avoid Cell Value Type Parsing

When you set a value in a cell, an internal parser determines the cell value type. If you already know the target type, set it explicitly. This bypasses parsing and improves performance.

The easiest way to do this is to use a SetValue() overload with the matching CLR type, such as DateTime or double. For formulas and text values, use SetValueAsFormula() and SetValueAsText().

For more information, see how cell value types work.