Performance Tuning for List Rollups

As one might expect, the performance of List Rollup is affected by two major components:

the number of Lists
the number of List Items that are included in a rollup
the number of columns displayed for each item
the type of column displayed

The actual time it takes to perform a rollup will vary depending on server hardware and general system load. Some servers may be able to quickly process rollups containing over 50 lists and some will experience noticeable delays processing as few as 20. The best way to determine the practical limit in your environment is to try rollups with a varying number of Lists.

Some tips to improve performance are listed in the table below:

Tip Explanation

Tip	Explanation
Review the types of columns displayed	SharePoint data is stored as text. When it is retrieved for display in a list rollup, non-text data (i.e., dates, KPIs) needs to be formatted. This sometimes takes more time than just getting the data. To improve performance, minimize the number of non-text columns, if possible if you have some date columns that you don’t need to sort, create a calculated column in the list(s) that converts the date to a text column. A typical formula for this is: `=IF([Review Date],TEXT([Review Date],"mm/dd/yyy"),"-")`
Review the number of columns displayed	Only display the columns that your end users really need to see. If you are rolling up Tasks assigned to [Me] (the logged in user), do you need to display the Assigned To column?
Review the number items displayed	If you are rolling up events, do you need to see events that occurred in the past?

Review the types of columns displayed

SharePoint data is stored as text. When it is retrieved for display in a list rollup, non-text data (i.e., dates, KPIs) needs to be formatted. This sometimes takes more time than just getting the data. To improve performance,

minimize the number of non-text columns, if possible
if you have some date columns that you don’t need to sort, create a calculated column in the list(s) that converts the date to a text column. A typical formula for this is:
```
=IF([Review Date],TEXT([Review Date],"mm/dd/yyy"),"-")
```

Review the number of columns displayed Only display the columns that your end users really need to see. If you are rolling up Tasks assigned to [Me] (the logged in user), do you need to display the Assigned To column?

Review the number items displayed If you are rolling up events, do you need to see events that occurred in the past?