<howardw39> wrote in message news:13664@forums.infragistics.com...I put together a grid using Outlook style grouping, with about 30 choosable columns. About a third of the columns have custom summaries, and about half of these use custom Formulas in conjunction with an UltraCalcManager. It works OK except for one problem. When I change the grouping, or the sort order of a group, the change may take a second or so (there are 6,000 rows in the underlying table) before the grid appears to have updated. That is OK. But then the CPU keeps chugging away for another 5 to 15 seconds. Worse, with certain groupings, the CPU keeps going apparently indefinitely, as if it is in a loop. The UI continues to be responsive, so something is going on in a background thread. Does anyone recognize this issue or have advice on how to fix it?. http://forums.infragistics.com/forums/p/1887/13664.aspx#13664