PowerServer Performance Tuning Guide
Technique #2: thin-out “heavy” UI logic

The following PowerBuilder functions can synchronize data between DataWindows: ShareData, RowsCopy/RowsMove, Object.Data, and SetItem. ShareData is the fastest and it is recommended to use it whenever you need to synchronize data between DataWindows. SetItem is the slowest and should be avoided as much as possible. If ShareData cannot be or should not be used for some reason, then consider using RowsCopy/RowsMove followed by Object.Data.