You can configure social collaboration such that each document download results in a new entry in the activity stream notifications queue table for the document. There is no mechanism for monitoring how many entries accumulate in the activity stream notifications queue table. Depending on your workload and hardware capabilities, the activity stream backlog can increase in size to the point where you can experience degraded overall system performance .
You can reduce the activity stream notification backlog by adjusting the maximum number of sweep thread workers. By default, the maximum number of sweep thread workers is set to four. An increase in the maximum number of sweep thread workers to six can result in a significant reduction in the activity stream notification backlog. However, any further increase in the maximum number of sweep thread workers to eight or higher can result in an increase in CPU utilization.
To adjust the maximum number of sweep thread workers: