Mixing : Automation : Automation Preferences : Thinning

Thinning
Thinning automatically reduces the overall number of breakpoints in an automation playlist (including Trim playlists) in order to improve system performance. The amount of thinning applied is determined by the Degree of Thinning setting in the Automation Preferences page. When using high amounts of thinning, the resulting automation may differ noticeably from the original automation moves. Thinning only applies to audio tracks, and does not affect MIDI tracks. For instructions, see Thinning Automation.