Joseph McDowell writes, “Microsoft claims Microsoft Project 2007 has the capacity of up to 400,000 tasks. However, we have a number of projects that when they get to about 1,000 tasks, things start to slow down, and when you get to 4,000 to 6,000 tasks, things slow down drastically. We’re running Project 2007 Professional on dual processor PCs with 2GB of memory. Are you aware of the practical limit for the number of tasks? One of the sales reps for Microsoft is now telling us, after we have purchased Microsoft Project 2007 in quantity that best practices is to have no more than 1,000 tasks. I have never seen that published by Microsoft, PMI, MPUG, or anyone else. Are you aware any published practical limits or have you any experience or thoughts in this area?”

Answer: In my experience 1,000 tasks are no problem. Technically I would think it is possible to have up to 400,000 tasks, but the practicality of managing so many tasks is doubtful.

The problem with more than 1,000 tasks, I find, is the management of the actual schedule. I wouldn’t recommend having more than 1,000 tasks, and, yes, the more tasks you have, the slower an MPP file will get. It’s the same with Excel.

If, however, you have more than 1,000 tasks, trying switching Auto Calculate off and only recalculate when you really need it. You will find that this will improve the performance.

In order to avoid more than 1,000 tasks, you may also consider a master project with two or more sub projects included. Not only will you be able to manage fewer tasks per sub-project, but it will also give you an overall view of all project tasks.