In 90% of cases, the problem lies in the source data. Use a "Smart Table": select a cell in the data and click Format → Convert to named range.

This also solves the issue of adding new rows, but if the data still contains heavy formulas like ARRAYFORMULA, the speed will drop again. It's better to move them to a separate sheet or replace them with static values.

When the pivot table stops seeing new records, it's often due to an incorrect range. A detailed breakdown of this and other reasons can be found in the guide on fixing a pivot table that does not update.

🔗 Source: excel.rf