If you are using P6 EPPM as a data source, consider the data in the database. A very complex EPS/WBS structure will increase the processing time because these hierarchical elements require global processing even when the changes are small. The average size of activities can increase the memory requirements of the calculation process. Larger projects will cause more volume of change because the entire project is recalculated based on any changes within the project. This does not include changes to non-scheduling data, such as activity codes and UDFs.