PO Suggestions suddenly taking 6-8 hours instead of under 2 hours

We have recently seen a large jump in the time it is taking to run PO Suggestions, it used to take under 2 hours with 1 processor but suddenly jumped up to 6-8 hours using 5 processors.
There have been no changes made to the server on the day this started to happen.
We are thinking it must be a problem with data, has anyone experienced something similar or does anyone have an idea of where we can look please.

i have seen this type of thing happen with data. Something to look for is:

  1. a significant sized demand (from Order or Job) for a part that has a Max order qty of 1 (or other low value).
  2. look for lots of jobs being created due to this.

A quick BAQ that does a summary count of records in the PartDtl table might help… if you summarize the count by Part Number, it might help point out what parts have a large number of suggestions.

Example of what you MIGHT see:

  1. someone created a sales order for WidgetA for 10000 pieces.
  2. WidgetA is manufactured part, but has a max lot size of 1
  3. WidgetA is made from ComponentB, and ComponentB also has a max lot size of 1, or a Days of supply of 0, or is marked as Purchase Direct…
  4. MRP creates 10000 jobs for widgetA, all the materials are listed 10000 times, causing 10000 purchase demands.

if you were to remove the order for WidgetA, everything would go back to normal… or change the lot sizes, or days of supply, etc.