Recommended Async Data Cleanup
The Async processes generate large amounts of data, such as the data associated with queues, actions requests, and triggers. This data is meant to be transient, however, so you should perform regular purges of this data. This can reduce storage space needed for the data and can make troubleshooting easier.
For example, if you have a recurring schedule that starts an action group that is reused each time it executes, then any action invoked in the background from this also joins the group. If you do not clean these up, not only do triggers build up but related action group member requests build up and just keep growing. Any time you need to glean information from the action group, there is an increasing number records to read.
To reduce the amount of async data on the system, if you do not need to save async history, turn it off. If you want to save history, purge it periodically.
For purging, take advantage of the various schedulable purge actions that are available on the Maintenance Requests tab of the Async Setup page). These include a finished trigger purge as well as ones that purge async data and many other types of data. Alternatively, there are several different purge actions available on the individual forms for triggers, action requests, and queues. For example, the Requests form has an action to purge orphaned requests.