Specify the automated keyframe creation

Automating audio changes in the Audio Mixer can create more keyframes than necessary in the audio track, degrading performance. To avoid creating unnecessary keyframes, thereby ensuring both quality interpretation and minimal performance degradation, set the Automation Keyframe Optimization preference. In addition to providing other benefits, this preference makes editing individual keyframes easier because they are less densely arranged on the keyframe graph.

Choose Edit > Preferences > Audio (Windows) or Premiere Pro > Preferences > Audio (Mac OS).
In the Automation Keyframe Optimizations area, select one or both of the following options, and then click OK:
Linear Keyframe Thinning

Creates keyframes only at points that don’t have a linear relationship to the start and end keyframes. For example, suppose you are automating a fade from 0 dB to –12 dB. With this option selected, Adobe Premiere Pro creates keyframes only at the points that represent an increase in value from the beginning (0 dB) and ending (–12 dB) keyframes. If you don’t select this option, Adobe Premiere Pro may create several incremental keyframes of identical values between those two points, depending on the speed at which you change the value. This option is selected by default.
Minimal Time Interval Thinning

Creates keyframes only at intervals larger than the value you specify. Enter a value between 1 and 2000 milliseconds.