As my family tree grew, performance declined. I solved this by borrowing a common gamer tactic of installing the program on an SSD (solid-state drive). They are typically many times faster than magnetic drives. This sped up performance quite a lot. On reflection, this probably indicates there is more performance that could be obtained by using another gamer tactic of employing a RAM drive. For some reason, FTM does not use all of the available RAM. I infer from these observations that FTM is using inefficient memory management. A useful performance experiment you can perform is to export a large Gedcom (mine is 13,000 people) and run GenMerge on it. In addition to showing you common structural errors, GenMerge will show you that 15mb of Gedcom data can be read, analyzed, and reports written in well under a minute.