QTableWidget was a major bottleneck for large merge sources (#217). This is because a QTableWidgetItem needed to be created for every field in every record of the merge data, whether they are being displayed or not. This was not a problem for small merge sources (only a few dozen records max), however for larger data sets this would severely affect performance and make the application unresponsive. QTableView only renders the fields and records currently visible.
Jaye Evins