(optional) If a report is large and previewing it consumes a lot of memory, bind the DocumentViewer control to the CachedReportSource component instead. This component allows you to avoid memory consumption-related issues by storing pages in a file system or database during document generation.
Check the Cache Document Source option in the Document Viewer's smart tag after setting the Document Source property:
This adds the CachedReportSource component to the form. You can now change the component’s settings. Choose one of the following ready-to-use document storages the Storage property provides: