Any public static members of this type (Shared in Visual Basic) are safe for multi-threaded operations. However, instance members are not guaranteed to be thread safe. For example, changing a property value in one thread while an Export method is running in a separate thread could yield unexpected results.

Optimizing your report for exporting to Excel:
Since Excel is basically a table of rows and columns and ActiveReports is a free form type output, it may be necessary to “optimize” your ActiveReport for Excel exporting. When you want two controls to be in the same column when exported to Excel, it is imperative that the two controls have exactly the same Left property value. It may also help to ensure that the font of the two controls is the same. Attempting to make the height of the two controls similar will often times lead to a cleaner looking output in Excel. Similarly if you want two controls to be in the same row when exported to Excel, you should make sure that the two controls have exactly the same Top value, that their font is the same, and that their width is similar if not the same. Using RichText controls in your ActiveReports often results in poorly formatted output in Excel. Using the Page object's drawing methods to draw anything in the margin areas of the export will cause pagination problems. To keep the pagination accurate when printing Excel-exported output with items drawn on the page, do not draw them in the margin area.

Reference